Korn, Dieter, and Jürgen Bockwinkel. “The Early Gephuroceratid Ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea)”. European Journal of Taxonomy 823, no. 1 (June 8, 2022): 10–47. Accessed April 24, 2026. https://ejt.sandbox.publicknowledgeproject.org/index.php/ejt/article/view/1811.