1. Barnes LG, Hutchison JH, Howard H, Welton BJ (1981) The vertebrate fossils of the marine Cenozoic San Mateo Formation at Oceanside, California. In: Abbott PL, O’Dunn S (eds) Geologic Investigations of the Coastal Plain, San Diego County, California. San Diego Association of Geologists, San Diego, pp 53–70
2. Barnes LG, Ray CE, Koretsky IA (2006) A new Pliocene sea lion, Proterozetes ulysses (Mammalia: Otariidae) from Oregon, U.S.A. In: Csiki Z (ed) Mesozoic and Cenozoic Vertebrates and Paleoenvironments: Tributes to the Career of Prof Dan Grigorescu. Ars Docendi, Bucharest, pp 57–77
3. Berta A, Morgan GS (1985) A new sea otter (Carnivora: Mustelidae) from the late Miocene and early Pliocene (Hemphillian) of North America. J Paleontol 59: 809–819
4. Boessenecker RW (2007) New records of fossil fur seals and walruses (Carnivora:Pinnipedia) from the late Neogene of northern California. J Vertebr Paleontol 27(Suppl to no 3): 50A
5. Boessenecker RW (2011) New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of northern California and comments on otariid dental evolution. J Vertebr Paleontol 31(2): 454–467