Google Arts and CultureMemorandum from Arthur Griffith to de Valera on Ulster open_in_new document, 8 November 1921
Flickr - NLIMilitary carrying out official reprisal following an ambush in Meelin, Co. Cork photograph, January 1921
RTE Century Ireland Introducing de Valera – The East Clare by-election and the rise of an Irish political leader open_in_new article, 2017