Kastelein, T.J. “I. Hasenberg Butter, Academic Economics in Holland 1800-1870”. BMGN - Low Countries Historical Review 86, no. 3 (January 1, 1971): 431–434. Accessed April 20, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-101860.