Trewartha, Glenn T., author
McGraw-Hill, 1967
Buku Teks
oleh Glenn T. Trewartha [and others]
McGraw-Hill, 1977
Buku Teks
Duckson, Don W., author
McGraw-HIll, 1999
Buku Teks
Strahler, Arthur N., author
John Wiley & Sons, 1967
Buku Teks
Strahler, Arthur N., author
John Wiley & Sons, 1973
Buku Teks