Reference

Volker Dietze, Robert B. Chandler, Günter Schweigert, Wolfgang Auer (2001): New Stephanoceratids (Ammonitina) from the Lower Bajocian of Bruton (Somerset, S England) and Achdorf (Wutach area, SW Germany) – Stuttgarter Beiträge Naturkunde Serie B [Paläontologie] – 312_B: 1 - 21.