“De Economische En Fiscale Politiek Van De Graven Van Holland in De Dertiende Eeuw”. BMGN - Low Countries Historical Review 108, no. 1 (January 1, 1993): 3–12. Accessed December 22, 2024. https://ojstest.minions.amsterdam/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-104134.