prácticas comuns entre el clergat. «[https://sourcebooks.fordham.edu/source/homo-damian1.asp Medieval Sourcebook: Peter Damian: Liber Gomorrhianus [.c.1048-54]]»
Fiske Guide to Colleges 2005 (Twenty-first Edition). Naperville, IL: Sourcebooks, Inc, 2004. ISBN 1-4022-0229-6. Viles, Jonas.. The University Of Missouri
d'Hongria Bridei VII Ibn Sad, historiador Turgesius Calise, J. M. P.. Pictish Sourcebook, Documents of Medieval Legend and Dark Age History. Londres: Greenwood