References
- Wright , H. E. , Cushing , E. J. and Livingstone , D. A. 1967 . In Handbook of Paleontological Techniques , Edited by: Kummel , B. and Raup , D. 494 – 520 . San Francisco, California : W. H. Freeman and Co. .
- 1967 . Standard Methods for the Examination of Water and Wastewater , 12th Ed. , 673 New York, N. Y. : Amer. Pub. Health Assoc. .