APA

Dunbar C. O., . (1961). Principles of stratigraphy. New York: John Wiley & Sons, Inc.

Chicago

Dunbar Carl O, . 1961. Principles of stratigraphy. New York: John Wiley & Sons, Inc.

Harvard

Dunbar C. O., . (1961). Principles of stratigraphy. New York: John Wiley & Sons, Inc.

MLA

Dunbar Carl O, . Principles of stratigraphy. New York: John Wiley & Sons, Inc. 1961.