APA

Levin H. L., George Washington University, . (1990). Contemporary physical geology. Estados Unidos: Saunders College Publishing.

Chicago

Levin Harold L, George Washington University, . 1990. Contemporary physical geology. Estados Unidos: Saunders College Publishing.

Harvard

Levin H. L., George Washington University, . (1990). Contemporary physical geology. Estados Unidos: Saunders College Publishing.

MLA

Levin Harold L, George Washington University, . Contemporary physical geology. Estados Unidos: Saunders College Publishing. 1990.