KIEFT, C. van de. De feodale maatschappij der middeleeuwen. BMGN - Low Countries Historical Review, [S. l.], v. 89, n. 2, p. 193–211, 1974. DOI: 10.18352/bmgn-lchr.1815. Disponível em: https://bmgn-lchr.nl/article/view/URN%3ANBN%3ANL%3AUI%3A10-1-101975. Acesso em: 20 apr. 2024.