Gaya APA

Enger, E, D., Smith, B, F. (2004). Environmental Science : A Study of Interrelationships (Ed.9). New York: McGraw-Hill.

Gaya MLA

Enger, Eldon, D.., Smith, Bradley, F.. "Environmental Science : A Study of Interrelationships". Ed.9 New York: McGraw-Hill, 2004. Text.