Sources
https://history.state.gov/milestones/1914-1920/league
http://www.historylearningsite.co.uk/leagueofnations.htm
http://avalon.law.yale.edu/20th_century/leagcov.asp#art1
http://www.indiana.edu/~league/
http://www.pbs.org/wgbh/amex/wilson/portrait/wp_league.html
http://www.bbc.co.uk/schools/gcsebitesize/history/mwh/ir1/manchuriarev1.shtml
http://americanhistory.about.com/od/worldwari/tp/causes-of-world-war-1.htm