Cita APA (7a ed.)

Shrock, R. R., & Twenhofel, W. H. (1953). Principles of invertebrate paleontology: A revised and enlarged edition of Twenhofel and Shrock, Invertebrate Paleontology (2nd ed.). McGraw-Hill Book Company.

Cita Chicago Style (17a ed.)

Shrock, Robert R., y William H. Twenhofel. Principles of Invertebrate Paleontology: A Revised and Enlarged Edition of Twenhofel and Shrock, Invertebrate Paleontology. 2nd ed. New York ; Toronto ; London: McGraw-Hill Book Company, 1953.

Cita MLA (9a ed.)

Shrock, Robert R., y William H. Twenhofel. Principles of Invertebrate Paleontology: A Revised and Enlarged Edition of Twenhofel and Shrock, Invertebrate Paleontology. 2nd ed. McGraw-Hill Book Company, 1953.