Pelt, W. “M. Keyser, J.F. Heijbroek, I. Verheul, Frederik Muller (1817-1881). Leven En Werken”. BMGN - Low Countries Historical Review 113, no. 4 (January 1, 1998): 572–573. Accessed December 22, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-105572.