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 May 22, 2026. https://europeanjournaloftaxonomy.eu/index.php/ejt/article/view/1811.