1. U.S. Geol. Surv. Profess. Papers No. 424-B B-10 1961
2. Van Houten, F. B., Bull. Am. Assoc. Petrol. Geologists 40: 2801 (1956).
3. Swain, F. M., J. Paleontol. 23: 172 (1949).
4. Calif. Div. Mines Bull. 1951 154
5. Yen, T. C., J. Paleontol. 20: 495 (1946).