Cita APA (7th ed.)

Spencer, E. W. (2003). Earth science: Understanding environmental systems. McGraw - Hill.

Cita Chicago (17th ed.)

Spencer, Edgar W. Earth Science: Understanding Environmental Systems. Boston: McGraw - Hill, 2003.

Cita MLA (9th ed.)

Spencer, Edgar W. Earth Science: Understanding Environmental Systems. McGraw - Hill, 2003.