E. B. A. Bisdom, A. Gerlofsma, J. N. B. Poelman and P. A. Riezebos (1978) “Composite grains in heavy-mineral concentrates and their significance in the differentiation of surface deposits at the confluence of the Maas (Meuse) and Roer (Rur) rivers.”, Netherlands Journal of Geosciences, pp. 407-416. Available at: https://njgjournal.nl/index.php/njg/article/view/14167 (Accessed: 1April2026).