1. Aptian ammonites from the Argentinian Austral Basin. The Subfamily Helicancylinae Hyatt, 1894;Aguirre-Urreta;Annals of the South African Museum,1986
2. Fauna Aptiano-Albiana del Cerro Las Conchas;Almazán-Vázquez,1990
3. Lower Cretaceous deposits in California and Oregon;Anderson,1938
4. Upper Cretaceous of the Pacific Coast;Anderson,1958