Technology on the cattle ranch: 19th century. Timmons, Todd. "Technology on the Cattle Ranch: 19th Century ." Daily Life through History, ABC-CLIO, 2016, dailylife.abc-clio.com/Search/Display/1378450. Accessed 8 Dec. 2016.
Malaria Andrew, Susan. "Malaria." The Gale Encyclopedia of Science, edited by K. Lee Lerner and Brenda Wilmoth Lerner, 5th ed., Gale, 2014. Science in Context
Microorganisms Steinkraus, Keith H. "Microorganisms." Encyclopedia of Food and Culture, edited by Solomon H. Katz, vol. 2, Charles Scribner's Sons, 2003, pp. 507-513. World History in Context
The Rise and Practice of Inocuation in the 1700s "The Rise and Practice of Inoculation in the 1700s." Science and Its Times, edited by Neil Schlager and Josh Lauer, vol. 4, Gale, 2001. Science in Context,
Agricultural Production - crops "Agricultural Production—Crops." Encyclopedia of Global Industries, 5th ed., Gale, 2011, pp. 1-11. Global Issues in Context
Bow and Arrow / Crossbow Nickel, Helmut. "Bow and Arrow/Crossbow." Dictionary of the Middle Ages, edited by Joseph R. Strayer, Charles Scribner's Sons, 1989. World History in Context
Bow and Arrow "Bow and arrow." World of Invention, Gale, 2006. Science in Context,
Rifle "Rifle." World of Invention, Gale, 2006. Science in Context