Vries, B.M.A. de. “H. Gras, Geschiedenis Van Assen”. BMGN - Low Countries Historical Review 117, no. 1 (January 1, 2002): 78–80. Accessed December 22, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-106444.