Strahler, Arthur N.
John Wiley & Sons, 1975
Buku Teks
Petersen, James F.
Brooks/Cole Cengage Learning, 2012
Buku Teks SO
Whittow, John B.
Allen Lane, 1984
Buku Referensi
Blij, Harm J.. de
John Wiley & Sons, 1996
Buku Referensi
Trewartha, Glenn T.
McGraw-Hill, 1967
Buku Teks SO