In the Shadow of Death Mountain: The Dyatlov Pass Incident

In February of 1959, a group of skiers perished under strange circumstances in the shadow of Kholat Syakhl in what would come to be known as the Dyatlov Pass Incident. Bizarre behavior, inexplicable injuries, strangely colored skin, missing tongues, radiation, lights in the sky? What really happened on Death Mountain?

THE EXPEDITION

In 1959, a party of ten students from the Ural Polytechnic Institute (now Ural State Technical University), led by Igor Dyatlov (23), set out for a two-week excursion into the northern Ural Mountains.

Dyatlov's group consisted of Yuri Doroshenko (21), Lyudmila Dubinina (20), Alexander Kolevatov (24), Zenaida Kolmogorova (22), Yuri Krivonischenko (23), Rustem Slobodin (23), Nikolai Thibeaux-Brignolles (23), Semyon Zolotaryov (38), and Yuri Yudin (21).

They set out from Yekaterinburg on their arduous, high-difficulty trek into conditions that reached -22° F (-30° C) on 28 January 1959. Dyatlov planned for the expedition to explore the slopes of Gora Otorten, a mountain whose name purportedly means "Don't Go There" in the language of the local indigenous tribe, the Mansi. He planned for them to be back in contact via telegram from the village of Vizhay on 12 February, but also warned friends that the expedition might take longer than expected.

Before they fully made it into the wilderness, one of their members, Yuri Yudin, fell ill and had to stay behind at a village while the others went on. He would be the only member of the expedition to survive.

According to photographs developed from film rolls recovered from the scene by investigators, the group made camp on the slopes of a mountain roughly 8 miles (13 km) from Otorten in the early evening of 2 February. This mountain was called Kholat Syakhl by the Mansi, which has variously been translated as "The Mountain of the Dead," "Dead Mountain," or "Death Mountain."

Why they chose this location has puzzled many, since it was only around a mile from the tree line, which would have provided more shelter, and there is no evidence that they were pressed for time. In an interview with the St. Petersburg Times, Yudin stated his opinion that "Dyatlov probably did not want to lose the distance they had covered, or he'd decided to practice camping on the mountain slope" (Mead, 2008). This would turn out to be their final camp.

The group did not make contact on 12 February as planned, but since Dyatlov had warned that there might be delays, it wasn't until the 20th that friends and family became truly worried. A search-and-rescue team comprised of teachers, students, and volunteers began to look for the group, later joined by police and military.

THE DISCOVERY

When rescuers found the expedition's abandoned camp on 26 February, the scene they found baffled them. The tents, collapsed and half buried under snow, had apparently been cut open from the inside and the gear inside abandoned. Footprints from eight or nine people trailed from the tents and headed downslope toward the tree line. The footprints suggested that some were only wearing socks while others were barefoot. It appeared as if the campers had torn their way out of the tents and run off into waist-deep snow without their shoes, despite there being no evidence of foul play or other reason to panic. Investigators were able to match the prints with members of the group, excluding the possibility that someone else had entered the camp.

Soon, the rescue team found the bodies of Krivonischenko and Doroshenko roughly a mile from camp at the tree line, under a giant pine. Investigators noted that the trail of footprints had disappeared around halfway from the camp to where the bodies were found. This is most likely due to the weather that occurred in the three weeks before the investigators arrived. Both bodies were found barefoot and dressed only in their underwear. Reports state that branches high up in the tree were broken, suggesting that someone had tried to climb it, perhaps to orient themselves. Nearby were the remains of a fire.

Dyatlov, Slobodin, and Kolmogorova were found at points between the camp and the pine, lying as if they had been trying to return to camp. At this point, they were unable to find the others. A criminal investigation was opened, but autopsy reports failed to find any indication of foul play. The five had died of hypothermia. Slobodin had a fractured skull, but it was not a fatal wound.

It was another two months before the snow melted enough for the remaining four skiers to be found. Thibeaux-Brignolles, Dubinina, Zolotaryov, and Kolevatov were in a gully a few hundred feet downslope from the large pine, buried beneath a dozen feet of snow. They all suffered traumatic deaths, despite there being no outward signs of such. Thibeaux-Brignolles had a severely fractured skull, while Zolotaryov and Dubinina were found with crushed ribs. They were better outfitted than the other five had been, apparently having taken clothing from the dead. Zolotaryov was wearing Dubinina's coat and hat, while she in turn had been wearing a piece of Krivonishenko's wool pants wrapped around her foot. Adding to the strangeness, their clothes were apparently slightly radioactive.

This detail, as well as reports that Dubinina's tongue was missing, has fueled many of the wilder theories out there. Although, there are reasonable explanations for both details.

Camping lanterns contain thorium, a naturally occurring, slightly radioactive metal. In lanterns, although perfectly safe for use, it emits enough alpha particles to warrant an actual radiation warning label. Thorium gas mantles are ubiquitous - manufactured in many countries, they were invented in 1891 and are still in use today. (Around half of the 50 million lanterns sold in 2000 used thorium mantles.) So, it would be entirely likely that the lanterns they were using contained thorium.

These mantles are little fabric bags that serve as the wick. They're very fragile and it's pretty easy to turn one into dust when you touch it, as might happen when changing the wick. This dust then gets everywhere - like onto your clothes and the clothes of anyone else who happens to be in a tent with you.

As for Dubinina's missing tongue - in actuality, it wasn't just her tongue. According to autopsy reports, her eyes as well as the soft tissue around her eyes, eyebrows, the bridge of her nose, upper lip, and cheek were missing as well. These areas could simply have decomposed more quickly than the rest of her body because of contact with the running water where the body was found. Or it was possibly the result of scavengers, who tend to go for the soft tissues first. (As has been found during scientific investigations of purported "cattle mutilations.")

There were claims from those who attended the victims' open-casket funerals that the bodies were unusually tanned. Some even went so far as to claim that they were bright orange. But it is likely that any "unusual" tanning was actually the quite normal effect of days of winter sunburn or a normal part of decomposition processes under those conditions. Brian Dunning (2008) of Skeptoid also makes a good point about the mortician who prepared the bodies having to cover up not only frostbite but months of exposure and decomposition.

After a few months, the investigation concluded. Authorities stated that there was no evidence of foul play, ruling out one of their initial theories, which was that the local Mansi had killed the skiers in revenge for trespassing on their land. (It turned out that neither mountain was sacred or taboo to the Mansi.) Further discrediting the theory of foul play, a doctor who performed postmortem examinations, Boris Vozrozhdenny, decreed that the injuries could not have been inflicted by a human, due both to the force required and the lack of soft tissue injuries. According to case documents, he stated: "It was equal to the effect of a car crash." (Osadchuk, 2008). The deaths were put down to natural forces, the case was closed, and the files were classified. The area of the camp has officially been named Dyatlov Pass.

Records relating to the investigation were released in the 1990s, but shed little light on the case.

THE THEORIES

In 2009, Richard Holmgren and Adreas Liljegren made an expedition to the site and, after investigating, posited that the skiers were overtaken by a violent katabatic wind event.

Katabatic wind happens at night when highlands cool down by shedding heat via radiation. The air touching these highlands is also cooled and becomes denser than the air that is at the same elevation but is away from the slope. It then begins to flow downhill to the valley bottom. "This effect is enhanced during winter over snow covered surfaces and after dry, clear nights" ("Katabatic winds," n.d.). Very rarely, katabatic winds can reach gale force.

Katabatic wind was implicated in a 1978 incident in Sweden that killed eight hikers. Holmgren and Liljegren claim that the topography of that incident site was very similar to Dyatlov Pass.

They theorize that since katabatic winds appear quickly, the Dyatlov campers would have only had time to secure the tent by collapsing it and covering it with snow to prevent it from being torn apart and blown away. They say that there was a flashlight left turned on and lying on top of the buried tent and that the hikers probably left it intentionally as a means of finding the tent when they returned. They also propose that the group constructed two bivouac shelters, one of which collapsed, leaving four of them buried with violent injuries.

It is unclear if the weight of a bivouac shelter would be enough to equal the force required for injuries that were compared to a car wreck. It also seems odd that they had time to collapse and bury a tent, leave a beacon, and build alternative shelter, but not time to put their clothes (or at least shoes) on.

In his 2013 book, Dead Mountain: The Untold True Story of the Dyatlov Pass Incident, filmmaker and producer Donnie Eichar proposed a theory that the Dyatlov Pass skiers were driven hysterical by infrasound resulting from a weather phenomenon called Kármán vortex streets.

Kármán vortex streets (or von Kármán vortex streets) occur when a fluid or gas (like wind) encounters an obstacle (like mountains) of a particular shape, which causes vortices in the flow. These oscillating vortices can be quite destructive and have been known to be the cause of bridge and building collapses.

Eichar posits that extremely high wind conditions occurred that night, interacting with the shape of Kholat Syakhl's summit and the group's tent to form a Kármán vortex street, which in turn produced a frequency of ultrasound that induced severe panic in the skiers and caused them to flee from the tents and to their deaths.

Whether or not the Kármán vortex street phenomenon can form under the conditions found in Dyatlov Pass, or if it would actually produce infrasound if it did form, is unclear.

What is more clear is what we know about the effects of infrasound on the human body. Infrasound is a wave phenomenon that has the physical nature of sound but is below the normal range of human hearing (i.e., below 16-20 Hz). It can cause nausea similar to motion sickness, anxiety, feelings of depression, and chills. It has been theorized to be the reason that some people feel a "presence" that they believe to be ghosts or even why they see them. (It literally vibrates your eyeballs!) However, no studies have ever shown infrasound to cause any sort of "hysteria." While it can cause anxiety and perhaps paranoia, it would in no way induce the sort of panic required to tear through a tent and run off into subzero temperatures in your underwear.

Another theory that has, of course, shown up due to the secrecy and radiation claims, is that Dyatlov's group inadvertently stumbled across some sort of military testing ground.

Proponents of this theory first point to the radiation found on some of the victims' clothing. But as pointed out earlier, a simple explanation for that can be found in their camp lanterns. It should also be noted that it's unclear at what levels or even what kind of radiation was found, so it's a bit difficult to attribute it definitively to any source. Not to mention that radioactive dispersal from a weapon would have likely affected all the skiers, their equipment, and the entire area, not just a few items of clothing.

They also point to the strange coloration of the bodies, but again we've already found some possible reasons for that - natural tanning, exposure of the bodies, and/or a mortician facing one heck of a challenge.

The Baikonur Cosmodrome in Kazakhstan was a test center for the world's first intercontinental ballistic missile and, at a distance of roughly 1,093 miles (1,749 km) from Kholat Syakhl, was the nearest facility with launch capabilities. Alexander Zeleznyakov, a senior official of the Korolyov Rocket and Space Corporation Energia who specializes in the history of Soviet missiles, stated that a surface-to-air missile launched from the Baikonur Cosmodrome today could have reached the northern Urals, but those types of missiles hadn't been invented yet. He also stated that there are no records of launches of any sort during that time frame.

During interviews, Yudin claimed that the military might have found the tent before the search-and-rescue volunteers. He said that he was told to identify the owner of every item at the site and could find no matches for several items - a pair of glasses, a piece of cloth that he believed came from a soldier's coat, a pair of skies, and a fragment of a ski. He also claimed that he saw documents that led him to believe the case had been opened fourteen days before searchers found the tent. The veracity of his claims is dubious at best since there has been no verification of any of the details.

In 2016, Yuri Kuntsevich, head of the Dyatlov Group Memory Public Fund, told Russian news agency TASS that he believes the group of skiers could have been on a mission for the KGB. He said that he had recently uncovered that there were two KGB officers in the Dyatlov group and that they were possibly in the Ural Mountains to "provide support for a technology-induced experiment. The tourists were carrying a large batch of photo equipment, which was completely atypical of highly complex expeditions that require maximally alleviating their load" ("Dyatlov Pass mystery," 2016).

According to Kuntsevich, the group was supposed to reach Otorten at an appointed time. Once they reached their destination, they were to wait for a "technology-induced" moment and capture pictures of it. But something went wrong and this led to their deaths.

Kuntsevich says that his claim is backed up by the fact that, of the ten rolls of film the group was known to be carrying, the whereabouts of only four are known. He believes that the missing film contains photos of whatever experiment was being performed, possibly relating to the strange light phenomenon that was reported in the area.

Kuntsevich, so far as can be determined, has not stated where he has gotten his information or provided any sort of verification of his claims.

In 1990, thirty-one years after the incident, Lev Ivanov, who was the lead investigator of the incident, was interviewed by Kazakh newspaper Leninsky Put. In the interview, Ivanov made claims that only fueled the fires of conspiracy theories and speculation.

He claimed that he was the first one to notice that the bodies and gear found were radioactive, saying that he'd brought a Geiger counter with him. (Media reports do not say why he had a Geiger counter on him and I couldn't find the original interview, but it was the Cold War era, so it wouldn't be surprising if there was a certain amount of paranoia.)

He also claimed that Soviet officials told him to "clamp the case shut" because they were concerned about reports that bright, spherical lights had been spotted in the sky over the area of Dyatlov Pass in February and March of 1959. Ivanov told Leninsky Put, "I suspected at the time and am almost sure now that these bright flying spheres had a direct connection to the group's death" (Mead, 2017).

Ivanov proposed that the fast-moving fireballs either exploded or emitted some sort of "energy weapon" that directly caused the skiers' deaths.

Another group of students, who were camping around 30 miles (50 km) south of the incident site, apparently reported sightings of the lights. Once claimed that he saw a "shiny circular body fly over the village from the south-west to the north-east. The shining disc was practically the size of a full moon, a blue-white light surrounded by a blue halo. The halo brightly flashed like the flashes of distant lightning. When the body disappeared behind the horizon, the sky lit up in that place for a few more minutes" (Mead, 2017). Other media reports state that the lights this group saw were strange orange spheres that traveled in the direction of Kholat Syakhl. It is unclear which of these descriptions, if any, were in the official reports.

Unfortunately for believers, Levanov's assumptions that the lights were spotted on 2 February - the day of the incident - has been challenged by mountaineer and author Evgeny Buyanov, who stated that he could find no verifiable reports of UFOs in the Urals on or near that date. There were also no traces of any explosion found at the site.

Of course, something strange can't happen in an icy mountain range without the Yeti showing up.

In June of 2014, Discovery Channel aired a so-called "documentary" called Russian Yeti: The Killer Lives, hosted by Mike Libecki, in which they propose that the Dyatlov group was attacked by a Yeti, also known as the Abominable Snowman.

As evidence, Libecki pointed to the trauma injuries and Dubinina's missing tongue, claiming that it had been ripped out by the Yeti. Quite aside from the natural explanations for the missing tongue, even if a Yeti existed this doesn't make much sense. As skeptic Benjamin Radford (2014b) pointed out in a Skeptical Inquirer special report:

If it was a tongue-hungry Yeti as Libecki suggests, why would it only have eaten one person's tongue when there were eight more nearby just ready for the ripping? Furthermore, the process of actually ripping out the woman's tongue (as Libecki suggests) would leave far greater injuries to Dubinina's mouth, jaw, and head than were found. A creature as powerful (and "enraged," as Libecki suggests) as the Yeti would likely have ripped her head clean off. To suggest that one or more Yetis killed nine people leaving "horrific injuries" yet gently and delicately opened one victim's mouth to remove her tongue beggars belief and defies logic.

There is no evidence that the traumatic injuries were caused by an attack - animal or otherwise. In fact, there is no evidence of anyone other than Dyatlov's group having been in the area. The lack of out-of-place or unidentifiable footprints is one of the reasons that authorities ruled out foul play in the first place. One would think that if a creature known for his footprints was stomping about, he would have actually left a footprint.

Libecki also pointed to the positioning of the final bodies to be found, claiming that the way they were crouched together showed that they were trying to hide from something that was trying to kill them. This does not seem more likely than the idea that they were huddling together for warmth.

Libecki also used as evidence a newspaper that the students had brought with them onto which had been written: "From now on we know that the snowmen exist." The program showed this as a typed sentence, in Russian, in a summary report of the case, and not the original newspaper. The full passage as written on the original document reads: "From now on we know that the snowmen exist. They can be met in the Northern Urals, next to Otorten Mountain." Given the newspaper's tone, it was more than likely a joking reference to themselves.

The show also revealed a photograph purported to be taken by the skiers, although there doesn't seem to be reference to it anywhere else. The photo shows what Libecki claims was a Yeti but looks like nothing more than a human being wrapped in cold weather gear. One would think that if a group of young students did, in fact, not only see a Yeti but captured it on film, they would have at least stopped to write it down in their diaries instead of going about their journey as if nothing happened.

THE MOST LIKELY EXPLANATION

In February 2019, Alexander Kurennoi, official representative of Russia's Prosecutor General, announced at a press conference that, due to public pressure, the case had been officially reopened and was being moved from the regional branch of the Investigative Committee to the federal branch.

He stated that they would only be seriously looking at three theories, all of which were attributable to natural phenomena - avalanche, snow slab, or hurricane. Officials narrowed down the possibilities to those options after ruling out an official list of 75 theories, which ranged from government conspiracy to supernatural events.

During a press conference, Andrey Kuryakov, head of the Prosecutor's Office of the Sverdlovsk Region, revealed a 400-page volume of original case materials. He stated that investigators would be relying on the help of friends and family of the Dyatlov victims and modern technology not available at the time of the incident.

In July 2020, the news agency RIA reported the renewed investigation's conclusions.

"The version (of the events) about the avalanche has found its full confirmation, but it was not the only cause of their death," said Kuryakov. (Devitt, 2020)

The inquiry supported the theory that the unfortunate hikers were the victims of a sudden slab avalanche, causing them to abandon their tents and take shelter under a nearby ridge. The lack of visibility meant that they were unable to return and eventually succumbed to the elements.

Despite these results, the general public seemed reluctant to accept an avalanche as being the explanation, with critics claiming that Russia's findings lacked "key scientific details." (Solly, 2021)

To test the findings and provide those key details, John Gaume, head of the Snow and Avalanche Simulation Laboratory at the Swiss Federal Institute of Technology, and Alexander M. Puzrin, a geotechnical engineer at ETH Zürich, recreated the mountain's environment on the night of the incident using data from historical records. They then used computer modeling to simulate a slab avalanche in those conditions. The simulation used snow friction data and local topography to show that a small snowslide sweeping over the area could have left few traces behind.

Gaume and Puzrin theorized that katabatic winds forced snow down the mountain over the campsite, and eventually the accumulated snow became heavy enough that the slope (which wasn't as shallow as it previously seemed) could not support it, collapsing and dropping a block of snow onto the unfortunate hikers.

However, another puzzle piece remained - the strange injuries that the hikers sustained, which didn't quite match up with typical avalanche injuries. The answer came with help from an unexpected source.

Gaume had watched the 2013 film Frozen and was so impressed by its depiction of snow that he contacted the movie's creators and asked for their animation code. Gaume and Puzrin used this code, as well as data from 1970s cadaver tests conducted by General Motors, to simulate what happens to the human body when struck at different speeds.

These simulations led them to posit that heavy blocks of solid snow could have landed on the tents as the hikers slept, causing injuries that aren't usually found in typical avalanche victims.

The pair suggested their own reconstruction of the incident:

During the night of February 1st, a slab of snow crashed down on the part of the tent facing the slope. Three of the students were partially buried and sustained severe, but not immediately fatal injuries. One of the hikers, in a panic, cut open the tent and the underdressed group went out into the freezing, pitch-black night. All nine ran roughly two miles (1 km) down the slope to the woods. There, under the cedar tree, two of them started a fire (sustaining burn injuries). Three hikers, realizing this would not be enough to keep them all alive, attempted to make their way back to the tent to retrieve supplies and clothing. Due to the low visibility (less than 55 ft or 16 m), they became disoriented and died on the slope. Four of the hikers went deeper into the woods to find shelter in a snow cave but eventually succumbed to their internal injuries. Later, rescuers disturbed the ground around the tent, and the snow slab's remains were mistaken as wind-blown snow.

Gaume and Puzrin published their results in a January 2021 issue of Communications Earth & Environment.

Puzrin stated: "The truth, of course, is that no one really knows what happened that night. But we do provide strong quantitative evidence that the avalanche theory is plausible." (Bressan, 2021)

Critics of the slab avalanche hypothesis claimed that those types of avalanches do not occur on Dyatlov Pass. However, Gaume and Puzrin proved them wrong after following up their hypothesis with multiple trips to the Pass. The final trip took place in early 2022, around the same time and under similar conditions as the original incident.

It was during this trip that they obtained critical evidence - video evidence of recent slab avalanches on Dyatlov Pass.

These findings, published in a 2022 issue of Communications & Environment, also refuted those who claimed that the slopes on the Pass are not steep enough for avalanches.

The expedition showed that the area is covered in step-like drops that could produce a slab avalanche. The large scale of these drops gives the slope a broad appearance that, under snow cover, would give the appearance of being safe. According to the study, the slopes are "not just local, they are continuous: no matter where you pitch your tent you are likely to be below one of them." (Puzrin & Gaume, 2022)

The study further states: "On the 28th of January 2022, exactly 63 years after the Dyatlov group was seen alive for the last time, two professional mountain guides from Ekaterinburg, Oleg Demyanenko & Dmitriy Borisov, left for the Dyatlov Pass on two snowmobiles. The initially favorable weather conditions quickly deteriorated, with wind and temperatures becoming similar to those on the night of the 1959 tragedy. Several times, the 300 kg [661.4 lb] snowmobiles and their drivers were overturned by wind gusts. Visibility became extremely poor. And then, when after a few failed attempts the two mountain guides approached their destination, the visibility briefly improved and revealed traces of two snow slab avalanches."

Demyanenko and Borisov filmed the remains of these avalanches and watched as they disappeared under snowfall within a mere hour after discovery. This explains why the initial investigators, studying the site three weeks after the fact, could find no trace of an avalanche. It also explains the previous belief that no such avalanches occur in the area - all traces of them are gone too quickly to catch.

Gaume and Puzrin pointed out that although many of the conditions leading to the observation of avalanches in 2022 were similar to those the Dyatlov group found themselves in, "[o]ther conditions were different: the slab was softer, the slope was steeper, it was not undercut from below and the trigger was probably different, too. Nevertheless, the area is clearly avalanche prone, and the avalanche danger on the night of February 1st, 1959 was real."

Gaume and Puzrin closed the study with these words: "Time and again, we were asked whether our article brings an end to our work on the case. We always responded that, although the case itself remains open, our part is closed: we did not want to spend the rest of our lives trying to solve the Dyatlov Pass mystery. One year later, we are no longer so sure. If someone asks, we will refrain from an answer."

SOURCES

Andrew, E. (2013, Oct. 22). Von Kármán vortex streets. Retrieved from https://www.iflscience.com/environment/von-k%C3%A1rm%C3%A1n-vortex-streets/

Bressan, David. (2021, Jan. 28). Mysterious deaths at Dyatlov Pass may finally be solved after 62 years thanks to a computer simulation. Forbes. Retrieved from https://www.forbes.com/sites/davidbressan/2021/01/28/mysterious-deaths-at-dyatlov-pass-may-finally-be-solved-after-62-years-thanks-to-a-computer-simulation/?sh=4217f7354d25

Carlier, Rémi. (2021, Jan. 28). Using science to explore a 60-year-old Russian mystery. EPFL. Retrieved from https://actu.epfl.ch/news/using-science-to-explore-a-60-year-old-russian-m-4/

cattle "mutilation". (n.d.). The Skeptic's Dictionary. Retrieved from http://www.skepdic.com/cattle.html

Devitt, Polina. (2020, Jul. 11). Russia blames avalanche for 1959 Urals mountain tragedy, RIA agency reports. Reuters. Retrieved from https://www.reuters.com/article/us-russia-accident-idUSKCN24C0IE/

Dunning, B. (2008, Jul. 8). Mystery at Dyatlov Pass. Skeptoid Podcast. Skeptoid Media. Retrieved from https://skeptoid.com/episodes/4108

Dyatlov Pass incident archive to be handed over to Yeltsin Center Museum. (2019, Feb. 1). TASS. Retrieved from https://tass.com/society/1042894

Dyatlov Pass mystery victims could have been on KGB mission - researcher. (2016, Jul. 21). TASS. Retrieved from https://tass.com/society/889813

Emery, D. (2017, Dec. 28). The Dyatlov Pass incident. Retrieved from https://www.snopes.com/news/2017/12/28/dyatlov-pass-incident/

Freidlander, E. (2019, Feb. 14). Russian investigators are reopening the Dyatlov Pass case. But what is it? The Moscow Times. Retrieved from https://www.themoscowtimes.com/2019/02/14/russian-investigators-are-reopening-dyatlov-pass-case-but-what-is-it-a64461

Gaume, J., Puzrin, A.M. Mechanisms of slab avalanche release and impact in the Dyatlov Pass incident in 1959. Commun Earth Environ 2, 10 (2021). https://doi.org/10.1038/s43247-020-00081-8

Hadjiyska, T. (n.d.). Dyatlov Pass: Theories - Katabatic wind. Retrieved from https://dyatlovpass.com/theories#katabatic

Ilyushina, M. & L. Kolirin. (2019, Feb. 4). Russia reopens investigation into 60-year-old Dyatlov Pass mystery. Retrieved from https://edition-m.cnn.com/2019/02/04/europe/dyatlov-pass-incident-scli-intl/index.html

Incandescent gas lantern mantles. (2009, Nov. 11). Retrieved from https://www.orau.org/PTP/collection/consumer%20products/mantle.htm

Infrasound. (n.d.-1). American Heritage Dictionary of the English Language, Fifth Edition. (2011). Retrieved July 10, 2019 from https://www.thefreedictionary.com/infrasound

Infrasound. (n.d.-2). McGraw-Hill Concise Encyclopedia of Physics. (2002) Retrieved July 10, 2019 from https://encyclopedia2.thefreedictionary.com/infrasound

Infrasound. (n.d.-3). The Skeptic's Dictionary. Retrieved from http://www.skepdic.com/infrasound.html

Ingis-Arkell, E. (2012, Feb. 17). The beautiful, deadly vortex that tears huge buildings apart. Retrieved from https://io9.gizmodo.com/the-beautiful-deadly-vortex-that-tears-huge-buildings-5885590

Katabatic wind. (n.d.). Encycylopedia Britannica online. Retrieved from https://www.britannica.com/science/katabatic-wind

Katabatic winds. (n.d.). Retrieved from https://www.weatheronline.co.uk/reports/wxfacts/Katabatic-winds.htm

Mayo Clinic. (2019, Mar. 13). Hypothermia: Symptoms and causes. Retrieved from https://www.mayoclinic.org/diseases-conditions/hypothermia/symptoms-causes/syc-20352682

Mead, D. (2017, Sept. 5). Russia's Dyatlov Pass incident, the strangest unsolved mystery of the last century. Retrieved from https://www.vice.com/en_nz/article/wjj9yb/russias-dyatlov-pass-incident-the-strangest-unsolved-mystery-of-the-last-century

Osadcuk, S. (2008, Feb. 19). Mysterious deaths of 9 skiers still unresolved. The St. Petersburg Times. Retrieved from https://web.archive.org/web/20080226101629/http://www.sptimes.ru/story/25093

Paradoxical undressing. (n.d.). Segan's Medical Dictionary. (2011) Retrieved July 10, 2019 from https://medical-dictionary.thefreedictionary.com/paradoxical+undressing

Prosecution agencies rule out authorities' involvement in 1959 Dyatlov Pass Incident. (2019, Feb. 4). TASS. Retrieved from https://tass.com/society/1043155

Puzrin, A.M., Gaume, J. Post-publication careers: follow-up expeditions reveal avalanches at Dyatlov Pass. Commun Earth Environ 3, 63 (2022). https://doi.org/10.1038/s43247-022-00393-x

Radford, B. (2014a, Jun. 1). Dyatlov Pass and mass murdering yeti? A DN exclusive. Retrieved from https://doubtfulnews.com/2014/06/dyatlov-pass-and-mass-murdering-yet-a-dn-exclusive/

Radford, B. (2014b, Sept./Oct.). Discovery's mountain of mystery mongering: The mass murdering yeti. Skeptical Inquirer 38(5). Retrieved from https://skepticalinquirer.org/2014/09/discoverys-mountain-of-mystery-mongering-the-mass-murdering-yeti//?%2FSI%2Fshow%2Fdiscoverys_mountain_of_mystery_mongering_the_mass_murdering_yeti

Solly, Meilan. (2021, Jan. 29). Have scientists finally unraveled the 60-year mystery surrounding nine russian hikers' deaths? Smithsonian Magazine. Retrieved from https://www.smithsonianmag.com/smart-news/scientists-may-have-finally-unraveled-mystery-dyatlov-pass-incident-180976886/

Thorium. (2017, Feb.). World Nuclear Association. Retrieved from https://www.world-nuclear.org/information-library/current-and-future-generation/thorium.aspx

Vasomotor center. (n.d.). Mosby's Medical Dictionary, 8th Edition. (2009). Retrieved July 10, 2019 from https://medical-dictionary.thefreedictionary.com/vasomotor+center

Yuri Yudin. (2013, Apr. 29). Obituaries. The Telegraph. Retrieved from https://www.telegraph.co.uk/news/obituaries/10026000/Yuri-Yudin.html

Zasky, J. (2014, Feb. 1). Return to Dead Mountain: Did panic inducing infrasound lead to the deaths of nine Russian hikers at Dyatlov Pass? Retrieved from http://www.failuremag.com/article/return-to-dead-mountain