Simons, W. “M.W. Grauwen, Norbertus Aartsbisschop Van Maagdenburg (1126-1134)”. BMGN - Low Countries Historical Review 95, no. 3 (January 1, 1980): 535–538. Accessed April 24, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-102361.