"World War I." YourDictionary, n.d. Web. 14 September 2018. <http://www.yourdictionary.com/world-war-i>.
World War I. (n.d.). Retrieved September 14th, 2018, from http://www.yourdictionary.com/world-war-i
The war from 1914 to 1918 between the Entente Powers of the British Empire, Russian Empire, France, Italy, the United States and other allied nations, against the Central Powers represented by the German Empire, Austria-Hungary, the Ottoman Empire, and Bulgaria.
English Wiktionary. Available under CC-BY-SA license.