M. De Craen, and R. Swennen. “Sedimentology and Diagenesis of the Ankeritized Basal Zechstein Conglomerate in the Campine Basin (Bree Borehole, NE Belgium)”. Netherlands Journal of Geosciences, vol. 71, Jan. 1992, pp. 145-60, https://njgjournal.nl/index.php/njg/article/view/12539.