"Durham University Archive". archive.is. Archived from the original on 13 July 2012. Retrieved 4 June 2017.{{cite web}}: CS1 maint: bot: original URL status unknown (link)
‘DERRY, Ven. Percy A.’, Who Was Who, A & C Black, an imprint of Bloomsbury Publishing plc, 1920–2016; online edn, Oxford University Press, 2014; online edn, April 2014 accessed 4 June 2017