So, You’re Lost in Time: Determine When You Are

Code companion to simplify calculating angular distance between stars can be found on the History Survival Guide Github repo

Dunn, Tony. Proper Motion Simulator,

Halley, Edmund. “Considerations on the Change of Latitudes of Some of the Principal Fixt Stars.” The Philosophical Transactions of the Royal Society of London, from Their Commencement in 1665 to the Year 1800, 1809, pp. 329–330.

“How to Calculate the Angular Distance Between Two Stars.” Astrometry and Phot Calculator,

Illingworth, Valerie. The Anchor Dictionary of Astronomy. Anchor Books, 1979.

“List of the Constellations.”,


So, You’re Riding the Rails: Hobo Signs and Symbols

A complete list of all symbols as PNG files can be found on the History Survival Guide Github repo

“Any Chalk Marks on Your Fence.” The Havre Herald, 15 Apr. 1908, p. 3,

Beard, Daniel Carter. The American Boys’ Book of Signs, Signals and Symbols. 1918.

“Boy Tramp.” The Stark County Democrat, 26 Feb. 1904, p. 3,

“Code of Hobo-Land.” Western Kansas World, 23 Apr. 1904, p. 6,

“Gate-Post Language.” Western Kansas World, 28 Jan. 1893, p. 2,

“Glad Hand or Marble Heart.” The Globe-Republican, 10 May 1895, p. 2,

Haskin, Frederic J. “Evening Star.” Answers to Question, 9 July 1931, p. 8,

“Hobo Sign Language Is Changed and Secret Marks Become Public Property.” El Paso Herald, 10 Aug. 1914, p. 12,

“Hobo Signs on Gate Posts.” The Guthrie Daily Leader, 25 Feb. 1902, p. 2,

“Hobo Signs.” Payette Enterprise, 20 June 1912, p. 2,

“Hoboes Have Secret Code: Lodge King Deciphers It.” The Seattle Star, 27 Nov. 1922, p. 2,

“Home News.” The County Paper, 1 Apr. 1881, p. 1,

“Inverted Pitchfork Is Sign Dreaded by Tramps.” The Washington Times, 29 July 1914, p. 9,

“Plodding Pierre’s Guidebook.” New-York Tribune, 8 Sept. 1921, p. 3,

“Remarkable Experience of a Business Man Disguised as a Tramp.” The Minneapolis Journal, 26 Nov. 1905, p. 49,

“Roundabout.” El Paso Daily Herald, 27 Sept. 1897, p. 4,

“Secret Code of Tramps.” The Inter-Mountain Farmer and Rachman, 2 Sept. 1902, p. 10,

“Signal Code of Trampdom.” The Kendrick Gazette, 4 June 1909, p. 3,

“Signs of the Hobo.” The Tacoma Times, 8 Mar. 1911, p. 5,

“Signs of Tramp World.” Dakota Farmers’ Leader, 13 Mar. 1908, p. 6,

“Signs of Tramps: How the Wanderers Mark Fences and Gate Posts.” Evening Star, 29 Sept. 1894, p. 16,

“Signs Used by Tramps.” New Ulm Review, 2 Aug. 1893, p. 5,

“‘The Following Signs Are Said to Be Tramp Signs.’” Juniata Sentinel and Republican, 1 Aug. 1873,

“The Tramp Problem.” Evening Star, 21 May 1905, p. 19,

“The Tramp Trust: A Million In It.” The Spokane Press, 13 Feb. 1910, p. 16,

“The Tramp’s Cipher.” Morris Tribune, 26 Mar. 1884, p. 4,

“The Tramp’s Signal Code.” The Great Falls Leader, 17 Jan. 1889, p. 2,

“Tramp Sign Writing.” The Washington Herald, 24 Apr. 1910, p. 6,

“Tramp Signs and Habits of Tramps.” Dodge City Times, 22 Nov. 1879, p. 5,

“Tramp Signs.” Brenham Weekly Banner, 25 Apr. 1879, p. 3,

“Tramps and Their Marks.” Morning Appeal, 13 Jan. 1882, p. 3,

“Tramps and Their Signs.” The Aegis & Intelligencer, 12 Sept. 1879, p. 1,

“Tramps’ Gatepost Signs.” Frostburg Mining Journal, 9 Aug. 1902, p. 4,

“Tramps Have Signs.” The Coalville Times, 29 Aug. 1902, p. 3,

“Tramps in Germany Have ‘Union’; Tip Off Their Brothers with Signs.” Pueblo Chieftain, 30 July 1921, p. 13,

“Tramps’ Signs.” The Great Falls Leader, 12 Feb. 1889, p. 2,

“What Tramps’ Signs Mean.” Richmond Times-Dispatch, 6 Dec. 1914, p. 54,


Folklore Survival Guide: How to Kill (or Cure) a Wendigo

“The Algonquin Legends of New England, or, Myths and Folk Lore of the Micmac, Passamaquoddy, and Penobscot Tribes.” The Algonquin Legends of New England, or, Myths and Folk Lore of the Micmac, Passamaquoddy, and Penobscot Tribes, by Charles Godfrey Leland, Houghton, Mifflin and Co., 1884, pp. 240–246.

Bird, Louis, and Tamara Robinson. “Our Voices—Cannibalism (Omushkego Oral History Project).” Omushkego Oral History Project,

Cooper, John M. “The Cree Witiko Psychosis.” Primitive Man, vol. 6, no. 1, 1933, pp. 20–24., doi:10.2307/3316222.

“Culture-Bound Syndromes.” Core Psychiatry E-Book, by Padraig Wright et al., Saunders Ltd., 2012, p. 356.

Guinard, Joseph E. “Witiko among the Tete-De-Boule.” Primitive Man, vol. 3, no. 3/4, 1930, pp. 69–71., doi:10.2307/3316416.

“Les Bourgeois De La Compagnie Du Nord-Ouest: Récits De Voyages, Lettres Et Rapports inédits Relatifs Au Nord-Ouest Canadien.” Les Bourgeois De La Compagnie Du Nord-Ouest: Récits De Voyages, Lettres Et Rapports inédits Relatifs Au Nord-Ouest Canadien, by L. R. Masson, Québec, Impr. Générale A. Coté Et Cie, 1889, pp. 249–250.

James R. Stevens, “ZHAUWUNO-GEEZHIGO-GAUBOW,” in Dictionary of Canadian Biography, vol. 13, University of Toronto/Université Laval, 2003–, accessed October 27, 2019,

Marano, Lou, et al. “Windigo Psychosis: The Anatomy of an Emic-Etic Confusion [and Comments and Reply].” Current Anthropology, vol. 23, no. 4, 1982, pp. 385–412., doi:10.1086/202868.

Rand, Silas, and Helen Webster. “Legends of the Micmacs.” Legends of the Micmacs, New York; London : Longmans, Green, 1884, pp. 196–197.

Rohrl, Vivian J. “The Cure and Feeding of Windigos: A Critique.” American Anthropologist, vol. 74, no. 1-2, 1972, pp. 242–244., doi:10.1525/aa.1972.74.1-2.02a01750.

Rohrl, Vivian J. “A Nutritional Factor in Windigo Psychosis.” American Anthropologist, vol. 72, no. 1, 1970, pp. 97–101., doi:10.1525/aa.1970.72.1.02a00120.

Turner, D. H. “Windigo Mythology and the Analysis of Cree Social Structure.” Anthropologica, vol. 19, no. 1, 1977, pp. 63–73., doi:10.2307/25604977.


So, Angles: Making a Protractor, as Simply as Possible

Blundeville, Thomas. Briefe Description of Universal Mappes and Cardes, 1589. Early English Books Online Text Creation Partnership, 2011.

Martin, George E. The Foundations of Geometry and the Non-Euclidean Plane. Springer, 2011.

Birkhoff, George D. “A Set of Postulates for Plane Geometry, Based on Scale and Protractor.” The Annals of Mathematics, vol. 33, no. 2, 1932, p. 329., doi:10.2307/1968336.


So, Pi: Pi to 4782ths Place

Bailey, David H., et al. “The Quest for Pi.” The Mathematical Intelligencer, vol. 19, no. 1, 15 June 1996, pp. 50–56., doi:10.1007/bf03024340.

Huberty, Michael D., et al. “100,000 Digits of Pi.” 100,000 Digits of Pi, 6 July 1997,

Rayman, Marc. “How Many Decimals of Pi Do We Really Need? – Edu News.” Jet Propulsion Laboratory, NASA, 17 Mar. 2016,


So, You’re Lost in Space:  How to Read the Pioneer Plaque

A complete PNG of the Pioneer Plaque can be found on the History Survival Guide Github repo

Berendzen, Richard. Life Beyond Earth and the Mind of Man: a Symposium Held at Boston University on November 20,1972. NASA, Scientific and Technical Information Office, 1973.

Dunbar, Brian. “Pioneer 10 Spacecraft Sends Last Signal.” NASA, NASA, 25 Feb. 2003,

Dunbar, Brian. “Pioneer-10 and Pioneer-11.” NASA, NASA, 26 Mar. 2007,

“How to Read a Pulsar Map.” PBS, Public Broadcasting Service, 2017,

Howell, Elizabeth. “Pioneer 10: Greetings from Earth.”,, 18 Sept. 2012,

Johnston, Robert. “Reading the Pioneer/Voyager Pulsar Map.” Reading the Pioneer/Voyager Pulsar Map, 30 Oct. 2007,

Milano, Dan, et al. “Messages From Earth: The Story Behind the Pioneer 10 Plaque.” Ceros Originals, 21 May 2019,

MILLS, B. Pulsar Distances, Spiral Structure and the Interstellar Medium. Nature 224, 504–505 (1969).

“Pioneer F Plaque Location.” Internet Archive, 25 Feb. 1972,

“Pioneer F Plaque Symbology.” Internet Archive, 25 Feb. 1972,

“Pioneer Plaque.” The Planetary Society Blog,

Rosenthal, Jake. “The Pioneer Plaque: Science as a Universal Language.” The Planetary Society Blog,,

Sagan, Carl, et al. “A Message from Earth.” Science, vol. 175, no. 4024, 1972, pp. 881–884., doi:10.1126/science.175.4024.881.

Siegel, Ethan. “Voyager’s ‘Cosmic Map’ Of Earth’s Location Is Hopelessly Wrong.” Forbes, Forbes Magazine, 17 Aug. 2017,


So, You Need a Magnet: How To Build an Electromagnet

Ampère André-Marie. The Story of His Love Being the Journal and Early Correspondence of Andre-Marie Ampere with His Family Circle During the First Republic (1793-1804). Readex Microprint, 1976.

Banas, Timothy. “How to Calculate the Force of an Electromagnet.” Sciencing, 2 Mar. 2019,

Bellis, Mary. “William Sturgeon and the Invention of the Electromagnet.” ThoughtCo, ThoughtCo, 23 Feb. 2019,

“Electromagnetic Terms and Actions Explained by Experts.” Honolulu Star-Bulletin, 1916. Library of Congress,

Emerson, D.W. The Lodestone, from Plato to Kircher. 16 Jan. 2019,

“Explaining the Electro-Magnet.” Chariton Courier, 1911. Library of Congress,

Gugie, John. “How to Make Solenoid Magnets.” HomeSteady, 27 June 2019,

Helmenstine, Anne Marie. “The Relationship Between Electricity and Magnetism.” ThoughtCo, ThoughtCo, 9 Nov. 2018,

Henry, John. “John Henry to Bejmanin Silliman, Sr, on Electro-Magnetisms .” Received by Bejamin Silliman, Sr., 10 Dec. 1830. Smithsonian Institution Archive,

Henry, John. “John Henry to Bejmanin Silliman, Sr, on Electro-Magnetisms.” Received by Bejamin Silliman, Sr., To Bejamin Silliman, Sr., 15 Jan. 1831. Smithsonian Institution Archives,

Henry, John. “John Henry to Parker Cleaveland on Electromagnetism.” Received by Parker Cleaveland, To Parker Cleaveland, 8 May 1832. Smithsonian Institution Archives,

Henry, Joseph. “Joseph Henry’s Letter to John R. Henry (July 9, 1831).” Received by John R. Henry, 9 July 1831. Smithsonian Institution Archives,

Humanities, National Endowment for the. “Radio Primer.” News about Chronicling America RSS, News-Times Print. Co., 1922,

“Joseph Henry: A Life in Science.” Smithsonian Institution Archives, 20 Mar. 2012,

Marsh, James. “No I. PORTABLE ELECTRO-MAGNETIC APPARATUS.” Transactions of the Society, Instituted at London, for the Encouragement of Arts, Manufactures, and Commerce, vol. 41, 1823, pp. 47–52.,

Maxwell, James Clerk. Treatise on Electricity and Magnetism. Hansebook, 2016.

Mills, Allan A. The Lodestone: History, Physics, and Formation. Annals of Science, 2004.

Noorlander, Emiel. “How to Make a Solenoid Engine.” The Practical Engineer, The Practical Engineer, 31 Oct. 2019,

“The Papers of Joseph Henry.” The Joseph Henry Papers Project, 15 June 2013,

Papiewski, John. “What Causes a Permanent Magnet to Lose Its Magnetism?” Sciencing, 29 Aug. 2019,

Perkins, B.A. “The Electric Current and Some of It’s Household Applications.” Lovelock Tribune, 1909. Chronicling America,

Quarters, Cindy. “Classifications of Magnets.” Sciencing, 2 Mar. 2019,

Sturgeon, William. “No. III. IMPROVED ELECTRO-MAGNETIC APPARATUS.” Transactions of the Society, Instituted at London, for the Encouragement of Arts, Manufactures, and Commerce, vol. 43, 1824, pp. 37–52.,

Torres Assis André Koch, et al. Ampere’s Electrodynamics: Analysis of the Meaning and Evolution of Ampère’s Force between Current Elements, Together with a Complete Translation of His Masterpiece: Theory of Electrodynamic Phenomena, Uniquely Deduced from Experience. C. Roy Keys Inc., 2015.

Wasilewski, Peter, and Günther Kletetschka. “Lodestone, Nature’s Only Permanent Magnet: What It Is and How It Gets Charged.” Geophysical Research Letters, vol. 26, no. 15, 1999, pp. 2275–2278.,


So, You Have Scurvy: Vitamin C Deficiency: Prevention and Treatment in a Hurry

Alos, Enriqueta, et al. “Citrus Fruit Ascorbic Acid Extraction and Quantification by HPLC.” BIO-PROTOCOL, vol. 5, no. 5, 2015,

Anne Marie Helmenstine, Ph.D. “Use Iodine Titration to Determine the Amount of Vitamin C in Food.” ThoughtCo, ThoughtCo, 21 June 2019,

“Ascorbic Acid.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine,

Bachstrom, Johann Friedrich. Observationes circa Scorbutum. 1734.

Baron, Jeremy Hugh. “Sailors’ Scurvy before and after James Lind – a Reassessment.” Nutrition Reviews, vol. 67, no. 6, 2009, pp. 315–332.,

Bartholomew, M. “James Lind’s Treatise of the Scurvy (1753).” Postgraduate Medical Journal, vol. 78, no. 925, 2002, pp. 695–696.,

Blane, Gilbert. Observations on the Diseases of Seamen, by Gilbert Blane, M.D.F.R.S.S. Lond. and Edin. Physician Extraordinary to the Prince and Princess of Wales, Physician to the Duke of Clarence, and One of the Commissioners of Sick and Wounded Seamen. Printed for Murray and Highley, No 32, Fleet-Street; by Luke Hansard, No 6, Great Turnstile, Lincoln’s-Inn-Fields, 1799.

Brand, J. C., et al. “Nutrients in important bushfoods.” Proceedings of the Nutrition Society Australia. 1982.

Brown, Stephen R. Scurvy: How a Surgeon, a Mariner, and a Gentleman Solved the Greatest Medical Mystery of the Age of Sail. Thomas Dunne Books/St. Martin’s Griffin, 2005.

Brennan, Dan. “Kakadu Plum: Benefits, Uses, and Side Effects.” WebMD, WebMD, 25 Oct. 2021,

Brickley, Megan, and Rachel Ives. “Skeletal Manifestations of Infantile Scurvy.” American Journal of Physical Anthropology, vol. 129, no. 2, 2006, pp. 163–172.,

Carpenter, Kenneth J. The History of Scurvy and Vitamin C. Cambridge Univ. Pr., 2003.

Drouin, Guy, et al. “The Genetics of Vitamin C Loss in Vertebrates.” Current Genomics, vol. 12, no. 5, 2011, pp. 371–378.,

“Fooddata Central.” FoodData Central,

Forest City press. (Forest City, Potter County, D.T. [S.D.]), 13 April 1917. Chronicling America: Historic American Newspapers. Lib. of Congress. <>

Gadsby, Patricia. “The Inuit Paradox.” Discover Magazine, Discover Magazine, 20 July 2020,

Geraci, Joseph R., and Thomas G. Smith. “Vitamin C in the Diet of Inuit Hunters from Holman, N.W.T.” ARCTIC, vol. 32, no. 2, 1979,

Henderson daily dispatch. (Henderson, N.C.), 20 Oct. 1934. Chronicling America: Historic American Newspapers. Lib. of Congress. <>

Hess, Alfred F., and Mildred Fish. “Infantile Scurvy: The Blood, the Blood-Vessels and the Diet.” Archives of Pediatrics and Adolescent Medicine, VIII, no. 6, 1914, pp. 385–405.,

Hodges, Robert E., et al. “Experimental Scurvy in Man.” The American Journal of Clinical Nutrition, vol. 22, no. 5, 1969, pp. 535–548.,

Hughes, R E. “James Lind and the Cure of Scurvy: An Experimental Approach.” Medical History, vol. 19, no. 4, 1975, pp. 342–351.,

Jackson, Frederick G, and Vaughan Harley. “An Experimental Inquiry into Scurvy.” Proceedings of the Royal Society of London, vol. 66, no. 424-433, 1900, pp. 250–265.,

“James Lind and Scurvy: 1747 to 1795.” The James Lind Library, 24 July 2018,

Lee, Seongeung, et al. “Effect of Different Cooking Methods on the Content of Vitamins and True Retention in Selected Vegetables.” Food Science and Biotechnology, 2017,

Lind, James. A Treatise on the Scurvy: In Three Parts: Containing an Inquiry into the Nature, Causes, and Cures of That Disease: Together with a Critical and Chronological View of What Has Been Published on the Subject. Classics of Medicine Library, 1980.

Newark evening star and Newark advertiser. [volume] (Newark, N.J.), 29 Oct. 1915. Chronicling America: Historic American Newspapers. Lib. of Congress. <>

Ortner, Donald J., and Mary Frances Ericksen. “Bone Changes in the Human Skull Probably Resulting from Scurvy in Infancy and Childhood.” International Journal of Osteoarchaeology, vol. 7, no. 3, 1997, pp. 212–220.,<212::aid-oa346>;2-5.

Ortner, Donald J., et al. “Probable Evidence of Scurvy in Subadults from Archeological Sites in Peru.” American Journal of Physical Anthropology, vol. 108, no. 3, 1999, pp. 321–331.,<321::aid-ajpa7>;2-7.

Pemberton, John. “Medical Experiments Carried out in Sheffield on Conscientious Objectors to Military Service during the 1939–45 War.” International Journal of Epidemiology, vol. 35, no. 3, 2006, pp. 556–558.,

Popova, Aneta Tincheva. “The Effect of Heating on the Vitamin C Content of Selected Vegetables.” World Journal of Advanced Research and Reviews, vol. 3, no. 3, 2019, pp. 027–032.,

Price, Catherine. “The Age of Scurvy.” Science History Institute, 18 Apr. 2019,

Rajakumar, Kumaravel. “Infantile Scurvy: A Historical Perspective.” Pediatrics, vol. 108, no. 4, 2001,

Roig, M. G., et al. “A Model Study on Rate of Degradation of L-Ascorbic Acid during Processing Using Home-Produced Juice Concentrates.” International Journal of Food Sciences and Nutrition, vol. 46, no. 2, 1995, pp. 107–115.,

Srinivasan, K., and Devi Vanitha. “Characterization of L-Ascorbic Acid Single Crystals Grown from Solution with Different Solvents.” Crystal Research and Technology, vol. 45, no. 9, 2010, pp. 946–952.,

Svirbely, Joseph L., and C.G. King. “The Preparation of Vitamin C Concentrates from Lemon Juice.” Journal of Biological Chemistry, vol. 94, no. 2, 1931, pp. 483–490.,

Teddy, Frederick Mamboleo, et al. “Vitamin C, Iron and Zinc Levels of Selected African Green Leafy Vegetables at Different Stages of Maturity.” African Journal of Biotechnology, vol. 17, no. 17, 2018, pp. 567–573.,

Tröhler, U. “Lind and Scurvy: 1747 to 1795.” Journal of the Royal Society of Medicine, vol. 98, no. 11, 2005, pp. 519–522.,

The Wisconsin weekly blade. [volume] (Madison, Wis.), 18 Jan. 1917. Chronicling America: Historic American Newspapers. Lib. of Congress. <>

Zilva, S. S. “The Isolation and Identification of Vitamin C.” Archives of Disease in Childhood, vol. 10, no. 58, 1935, pp. 253–264.,


So, Tap Code: Simple Morse Code-Like Guide

Harris, Carlyle S. Tap Code: The Epic Survival Tale of a Vietnam Pow and The Secret Code That Changed Everything. Zondervan, 2019.

Koestler, Arthur. Darkness at Noon. Macmillan, 2003,,

“The Tap Code.” American Experience, Public Broadcasting Service,


So, Find Your Latitude by Hand: Determine Latitude at Night

Allain, Rhett. “Figure out Where You Are with Nothing but a Watch and Protractor.” Wired, Conde Nast, 3 May 2018,

Barbara, Vanessa. “The Dazzle of the Southern Sky.” The New York Times, The New York Times, 27 Dec. 2014,

“A Beginner’s Guide to the Southern Hemisphere Sky.” Sky & Telescope, 11 Apr. 2022,

Evans, James. The History and Practice of Ancient Astronomy. Oxford University Press, 1998.

“Find Your Latitude Using Just the Stars.” The Science Explorer,

Hamacher, Duane W, and Carla Bento Guedes. “How Far They’ll Go: Moana Shows the Power of Polynesian Celestial Navigation.” The Conversation, 14 Apr. 2021,

Hurley, Steve. “The Changing Pole Star.” Explaining Science, 13 Jan. 2021,

“Is It True That Vega Will Be Our next North Star?” University of Southern Maine, University of Southern Maine,

Jim, Clark. “Is Polaris Visible from the Southern Hemisphere?”, 14 Dec. 2018,

Kiger, Patrick J. “Why Is the North Star So Stellarly Important?” HowStuffWorks Science, HowStuffWorks, 13 Sept. 2022,

Layton, Julia. “How to Use the Stars to Find Your Way.” HowStuffWorks, HowStuffWorks, 22 Apr. 2013,

Petersen, Carolyn Collins. “Polaris Is Our Pole Star… for Now.” ThoughtCo, ThoughtCo, 29 Aug. 2018,

“Rough Science: Latitude and Longitude Challenge.” PBS, Public Broadcasting Service,

“Say Hello to Sirius, a Future South Pole Star.” EarthSky, 2 Jan. 2022,

Sessions, Larry. “Use Big Dipper to Find Polaris in September.” EarthSky, 2 Sept. 2021,

Siegel, Ethan. “Will Future Humans See a Better Pole Star than Polaris?” Forbes, Forbes Magazine, 8 Nov. 2020,

Stein, Vicky. “Polaris: How to Find the North Star.”, Space, 24 Jan. 2022,

“Thuban Is a Former Pole Star.” EarthSky, 1 July 2021,

“Use the Southern Cross to Find Due South: Favorite Star Patterns.” EarthSky, 18 Apr. 2021,

Van Brummelen, Glen. Heavenly Mathematics: The Forgotten Art of Spherical Trigonometry. Princeton University Press, 2017.

“What Is the North Star and How Do You Find It?” NASA, NASA, 28 July 2021,

“‘Winter,” Says the President of the A.S. during a Recent Meeting.   ‘What Constellation Comes to Mind?” ‘Orion,” Someone Says.” “WINTER,” Says the President of the A.S. during a Recent Meeting. “What Constellation Comes to Mind?”,


So, Cistercian Numerals: Decoding an Antique Number System

Beard, Daniel Carter. The American Boys’ Book of Signs, Signals and Symbols. 1918,

King, David. (2019). DAVID KING 1995 – A forgotten Cistercian system of numerical notation.

King, David. (2019). 203 – KING 2001 (BOOK) – The Ciphers of the monks, a forgotten number-notation of the Middle Ages.

Miller, Kirk. Background for Unicode Consideration of Cistercian Numerals. 10 Dec. 2020,

Puiu, Tibi. “What Are Cistercian Numbers — the Forgotten Ciphers of Medieval Monks.” ZME Science, 21 Jan. 2021,