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Énay, R.; Howarth, M. K. Stevensites, Zittelites, and Gyrophylloceras, New Generic Names Proposed for Stevensia Énay, 2009, Zittelia Tavera Benitez, 1985, and Gyrophyllites Wiedmann, 1963 (Mollusca: Ammonoidea). paleocontributions 2018, No. 19, 1-2. https://doi.org/10.17161/1808.26312.