Leupen, P. “De Karolingische Villa Beek En De Stamvader Van De Bosoniden”. BMGN - Low Countries Historical Review 92, no. 3 (January 1, 1977): 373–393. Accessed January 23, 2022. https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-102166.