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

http://www.warmuseum.ca/firstworldwar/history/battles-and-fighting/land-battles/the-somme/

http://www.firstworldwar.com/battles/somme.htm

http://www.thecanadianencyclopedia.ca/en/article/battle-of-the-somme/

http://www.bbc.co.uk/history/worldwars/wwone/battle_somme.shtml

http://www.bbc.co.uk/history/worldwars/wwone/battle_somme.shtml