Cita APA (7th ed.)

Ludman, A., & Coch, N. K. (1982). Physical geology. McGraw-Hill.

Cita Chicago (17th ed.)

Ludman, Allan, i Nicholas K. Coch. Physical Geology. New York: McGraw-Hill, 1982.

Cita MLA (9th ed.)

Ludman, Allan, i Nicholas K. Coch. Physical Geology. McGraw-Hill, 1982.