P. Buurman and A. W. Janssen (1983) “The stratigraphic position of the enigmatic Tertiary deposits called Holset sands, and of related sands in Belgium”, Netherlands Journal of Geosciences, pp. 431-436. Available at: https://njgjournal.nl/index.php/njg/article/view/13404 (Accessed: 3April2026).