Diana E. Greenway: DURHAM: BishopsFasti Ecclesiae Anglicanae 1066-1300: volume 2: Monastic cathedrals (northern and southern provinces). Institute of Historical Research. Arkistoitu 19.7.2011. Viitattu 19.1.2012. (englanniksi)
oxforddnb.com
William of St CalaisOxford Dictionary of National Biography. Oxford University Press. Viitattu 25.1.2012. (englanniksi)
web.archive.org
Diana E. Greenway: DURHAM: BishopsFasti Ecclesiae Anglicanae 1066-1300: volume 2: Monastic cathedrals (northern and southern provinces). Institute of Historical Research. Arkistoitu 19.7.2011. Viitattu 19.1.2012. (englanniksi)