1. Stratigraphy and depositional environments of the phosphorite-bearing Monterrey Formation in Baja California Sur;Alatorre;Econ. Geol.,1988
2. The El Cien Formation, strata of Oligocene and Early Miocene age in Baja California Sur;Applegate,1986
3. Reconnaissance of geology and oil possibilities of Baja California, Mexico;Beal;Geol. Soc. Am. Bull.,1948
4. Oligocene plants from the upper Ruby River basin, south western Montana;Becker;Geol. Soc. Am.,1961
5. The Fossil Record;Benton,1993