¹ Shmoop Electromagnetism Learning Guide

² A. A Michelson, Am. J Sci., 122, 120 (1881).

³ Shmoop Newtonian Physics Learning Guide

⁴ Shmoop Nuclear Physics Learning Guide

⁵ Shmoop Newtonian Laws Learning Guide

⁶ Shmoop Editorial Team. "The Scarlet Ibis What's Up With the Ending?" Shmoop.com. November 11, 2008. Accessed December 17, 2015. /scarlet-ibis/ending.html.

⁷ Accessed December 17, 2015. http://vaticanobservatory.org/index.php/en/history-of-astronomy/197-the-galileo-affair.

⁸ Shmoop Nuclear Physics Learning Guide

⁹ Richard Firestone and Virginia Shirley, Table of Isotopes, Eight Edition. Wiley-Interscience, 1998.

¹⁰ B. Rossi, D. B. Hall, Hall, Phys. Rev., 59, 223 (1941).

¹¹ Powers, Thomas. Heisenberg's War: The Secret History of the German Bomb. New York: Alfred A. Knopf, Inc., 1993.

¹² Shmoop Editorial Team. "Common Core Standards : CCSS.Math.Content.HSA-APR.C.5." Shmoop.com. November 11, 2008. Accessed December 17, 2015. /common-core-standards/ccss-hs-a-apr-5.html.

¹³ "Einstein’s Special Theory of Relativity, the Original Paper (1905)." TheHotSpringnet Site Wide Activity RSS. Accessed December 17, 2015. http://www.casavaria.com/hotspring/2008/05/21/123/einsteins-special-theory-of-relativity-the-original-paper-1905/.

¹⁴ "Earth Fact Sheet." Earth Fact Sheet. Accessed December 17, 2015. http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html.