Énay, Raymond, and Michael K. Howarth. 2018. “Stevensites, Zittelites, and Gyrophylloceras, New Generic Names Proposed for Stevensia Énay, 2009, Zittelia Tavera Benitez, 1985, and Gyrophyllites Wiedmann, 1963 (Mollusca: Ammonoidea)”. Paleontological Contributions, no. 19 (April): 1-2. https://doi.org/10.17161/1808.26312.