MLA citations

http://www.wired.com/thisdayintech/2009/08/0826crecy_cannon/

http://en.wikipedia.org/wiki/History_of_cannon

http://www.navweaps.com/Weapons/WNBR_47-40_mk1.htm

http://en.wikipedia.org/wiki/Cannon

http://www.civilwar.org/battlefields/batterywagner/battery-wagner-history-articles/the-swamp-angel.html

http://en.wikipedia.org/wiki/Canon_lourd_de_12_Gribeauval

http://en.wikipedia.org/wiki/5%22/54_caliber_Mark_42_gun

http://en.wikipedia.org/wiki/Field_artillery_in_the_American_Civil_War

http://www.mindfully.org/Nucs/2003/GAU-8-Avenger.htm

http://en.wikipedia.org/wiki/GAU-8_Avenger