Cita APA (7th ed.)

Keller, E. A. (1999). Introduction to environmental geology. Prentice Hall.

Cita Chicago (17th ed.)

Keller, Edward A. Introduction to Environmental Geology. Upper Saddle River, N.J: Prentice Hall, 1999.

Cita MLA (9th ed.)

Keller, Edward A. Introduction to Environmental Geology. Prentice Hall, 1999.