American Geological Institute. (2012). Environmental science. Cengage Learning Asia Pte Ltd.
Cita Chicago (17th ed.)American Geological Institute. Environmental Science. Pasig City, Philippines: Cengage Learning Asia Pte Ltd, 2012.
Cita MLA (9th ed.)American Geological Institute. Environmental Science. Cengage Learning Asia Pte Ltd, 2012.
Atenció: Aquestes cites poden no estar 100% correctes.