Gaya APA

Enger, E, D., Smith, B, F. (2004). Environmental science: A study of interrelationships 9th edition (9th edition). Boston: McGraw-Hill Book.

Gaya MLA

Enger, Eldon, D.., Smith, Bradley, F.. "Environmental science: A study of interrelationships 9th edition". 9th edition Boston: McGraw-Hill Book, 2004. Printed Book.