DE LEEUW, Wilhelmus. P. dr. Renatus Ritzen O.F.M. Studies over de sociaaleconomische geschiedenis van Limburg, [S. l.], v. 6, p. 9–20, 1960. DOI: 10.58484/ssegl.v6i13042. Disponível em: https://testplatform.openjournals.nl/SSEGL/article/view/13042. Acesso em: 11 apr. 2026.