Gaya APA
Smith, B, F., Enger, E, D. (1998).
Environmental Science: A Study of Interrelationships (6th ed. - ).
Amerika:
Mac Grawhill.
Gaya MLA
Smith, Bradley, F.., Enger, Eldon, D..
"Environmental Science: A Study of Interrelationships".
6th ed. -
Amerika:
Mac Grawhill,
1998.
Buku Teks.