APA

Twenhofel W. H., Shrock R. R., . (1935). Invertebrate paleontology. New York and London: McGraw-Hill.

Chicago

Twenhofel William H, Shrock Robert R, . 1935. Invertebrate paleontology. New York and London: McGraw-Hill.

Harvard

Twenhofel W. H., Shrock R. R., . (1935). Invertebrate paleontology. New York and London: McGraw-Hill.

MLA

Twenhofel William H, Shrock Robert R, . Invertebrate paleontology. New York and London: McGraw-Hill. 1935.