De Blij, Harm J., author
John Wiley & Sons, 1996
Buku Referensi
Muller, Robert A., author
Random House, 1978
Buku Teks
Craghan, Michael, author
John Wiley & Sons, 2003
Buku Teks
Strahler, Arthur N., author
John Wiley & Sons, 1983
Buku Teks
Gabler, Robert E., author
Thomson , 2004
Buku Teks