Piper, D Z. (1993). Cooccurrence of Fe-, Fe-Ca-, and Ca-phosphate minerals in concretions within the Monterey Formation: A record of uplift of the Santa Maria Basin, California. Washington, DC: United States Government Printing Office.

Cooccurrence of Fe-, Fe-Ca-, and Ca-phosphate minerals in concretions within the Monterey Formation : A record of uplift of the Santa Maria Basin, California / by D. Z. Piper, C. M. Isaacs, and M. D. Medrano . — Washington, DC : United States Government Printing Office, 1993. — III, C15 S.; Ill., graph. Darst. — (Evolution of sedimentary basins - Santa Maria Province ; C)

Piper, David Z. Cooccurrence of Fe-, Fe-Ca-, and Ca-phosphate Minerals in Concretions Within the Monterey Formation: A Record of Uplift of the Santa Maria Basin, California.Washington, DC: United States Government Printing Office, 1993.