Cita APA (7th ed.)
Thornbury, W. D. (1969). Principles of geomorphology (2d ed.). New Age International.
Cita Chicago (17th ed.)
Thornbury, William D. Principles of Geomorphology. 2d ed. New Delhi: New Age International, 1969.
Cita MLA (9th ed.)
Thornbury, William D. Principles of Geomorphology. 2d ed. New Age International, 1969.
Atenció: Aquestes cites poden no estar 100% correctes.