Shale from
USA | |
| (2005) Mineral Resources Data System (MRDS), US Geological Survey. |
| |
| Keller, Margaret A. (1988) Geologic basis for the assessment of undiscovered oil and gas resources of the Ventura Basin Province, California, 1987 National Assessment. Department of the Interior, U.S. Geological Survey Open File Report 87-450 M. |
| (2005) Mineral Resources Data System (MRDS), US Geological Survey. |