Gaya APA

Oberlander, T, M., Muller, R, A. (1987). Essentials of Physical Geography (Ed. 2). United States of America: Random House.

Gaya MLA

Oberlander, Theodore, M.., Muller, Robert, A. "Essentials of Physical Geography". Ed. 2 United States of America: Random House, 1987. Text.