KNOTTER, Ad. Ten geleide. Studies over de sociaaleconomische geschiedenis van Limburg, [S. l.], v. 49, p. 3–5, 2004. DOI: 10.58484/ssegl.v49i12492. Disponível em: https://testplatform.openjournals.nl/SSEGL/article/view/12492. Acesso em: 11 apr. 2026.