Woude, A.M. van der. “Th.L.M. Engelen, Fertiliteit, Arbeid, Mentaliteit. De Vruchtbaarheidsdaling in Nederlands-Limburg 1850-1960”. BMGN - Low Countries Historical Review 106, no. 3 (January 1, 1991): 498–501. Accessed May 5, 2024. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-103904.