Gray, Jeremy (2016) "Histories of Modern Mathematics in English in the 1940s, 50s, and 60s" in Remmert, Volker R.; Schneider, Martina; and Kragh Sørensen, Henrik (eds.) Historiography of Mathematics in the 19th and 20th Centuries Birkhäuser. p.161. (ردمك 9783319396491) نسخة محفوظة 4 يناير 2020 على موقع واي باك مشين.
Gray, Jeremy (2016) "Histories of Modern Mathematics in English in the 1940s, 50s, and 60s" in Remmert, Volker R.; Schneider, Martina; and Kragh Sørensen, Henrik (eds.) Historiography of Mathematics in the 19th and 20th Centuries Birkhäuser. p.161. (ردمك 9783319396491) نسخة محفوظة 4 يناير 2020 على موقع واي باك مشين.