Cita APA (7th ed.)

Editors by W. H. Twenhopel. (1953). Principles of invertebrate paleontology: A revised and enlarged (2nd ed.). McGraw - hill.

Cita Chicago (17th ed.)

Editors by W. H. Twenhopel. Principles of Invertebrate Paleontology: A Revised and Enlarged. 2nd ed. New York: McGraw - hill, 1953.

Cita MLA (9th ed.)

Editors by W. H. Twenhopel. Principles of Invertebrate Paleontology: A Revised and Enlarged. 2nd ed. McGraw - hill, 1953.