Παραπομπή APA

Shrock and Twenhofel. (1953). Principles of Invertebrate Palaeontology. Mc Graw Hill.

Παραπομπή Chicago Style

Shrock and Twenhofel. Principles of Invertebrate Palaeontology. New York: Mc Graw Hill, 1953.

Παραπομπή MLA

Shrock and Twenhofel. Principles of Invertebrate Palaeontology. Mc Graw Hill, 1953.