M. J. M. Bless and J. Bouckaert (1983) “Recent exploration in pre-permian rocks around the Brabant Massif in Belgium, the Netherlands and the federal republic of Germany”, Netherlands Journal of Geosciences, pp. 51-63. Available at: https://njgjournal.nl/index.php/njg/article/view/13346 (Accessed: 31March2026).