L.J. Giebels, Beel, van vazal tot onderkoning. Biografie 1902-1977. BMGN-LCHR [Internet]. 1998 Jan. 1 [cited 2024 Sep. 30];113(1):138-9. Available from: https://ojstest.minions.amsterdam/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-105361