Fossil cranial walrus material from the North Sea and the estuary of the Schelde (Mammalia, Carnivora)
Van Bree, P.J.H.; Erdbrink Bosscha, D.P. (1999). Fossil cranial walrus material from the North Sea and the estuary of the Schelde (Mammalia, Carnivora). Beaufortia 49(1): 1-9