Dyfyniad APA

Twenhofel, W. H., & Shrock, R. R. (1953). Principles of invertebrate paleontology (2d ed.). McGraw-Hill.

Dyfyniad Arddull Chicago

Twenhofel, William H., and Robert R. Shrock. Principles of Invertebrate Paleontology. 2d ed. New York: McGraw-Hill, 1953.

Dyfyniad MLA

Twenhofel, William H., and Robert R. Shrock. Principles of Invertebrate Paleontology. 2d ed. McGraw-Hill, 1953.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.