Ph. Muchez, W. Viaene, M. Wolf, and J. Bouckaert. “Sedimentology, Coalification Pattern and Paleogeography of the Campine- Brabant Basin During the Visean”. Netherlands Journal of Geosciences, Jan. 1987, pp. 313-26, https://njgjournal.nl/index.php/njg/article/view/13114.