Reference

Wolfgang Riegraf, Cornelia Schmitt-Riegraf (1987): Rhynchoteuthis minima von DER MARCK, 1858 (rhyncholite, Cephalopod Jaw) from the Latest Campanian (Cretaceous) of Westphalia (NW Germany) – Stuttgarter Beiträge Naturkunde Serie B [Paläontologie] – 135_B: 1 - 35.