“E.J. Harenberg, Oorkondenboek Van Gelre En Zutphen Tot 1326, IV”. BMGN - Low Countries Historical Review 110, no. 1 (January 1, 1995): 91–92. Accessed June 30, 2024. https://ojstest.minions.amsterdam/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-104550.