van den Biggelaar , D.F.A.M., R.T. van Balen, S.J. Kluiving, A. Verpoorte, and G.M. Alink. “Gravel Size Matters: Early Middle Palaeolithic Artefacts Made from Local Rhine and Meuse Deposits in the Central Netherlands”. Netherlands Journal of Geosciences 96 (November 21, 2016): 261 -271. Accessed April 1, 2026. https://njgjournal.nl/index.php/njg/article/view/11777.