Houses of OireachtasCorrespondence between de Valera and Lloyd George open_in_new debate, 14 September 1921
National Museums IrelandThe last letter written by Seán Mac Diarmada (Sean MacDermott) letter, 11 May 1916
Bodleian Library blog 100 years ago: Constitutional Crisis and the Parliament Act of 1911 open_in_new article, 2011