Masanobu Yamamoto, Kath Ficken, Marianne Baas, Hendrik-Jan Bosch, and Jan W. de Leeuw. “Molecular Palaeontology of the Earliest Danian at Geulhemmerberg (the Netherlands)”. Netherlands Journal of Geosciences 75 (January 1, 1996): 255-267. Accessed April 3, 2026. https://njgjournal.nl/index.php/njg/article/view/12377.