De Blij, Harm J., author
John Wiley & Sons, 1995
Buku Teks
edited by R.J. Johnston, Derek Gregory, Geraldine Pratt, Michael Watts
Blackwell Publishing, 2000
Buku Referensi
edited by John A. Agnew, James S. Duncan
Wiley-Blackwell, 2011
Buku Teks
Peter Daniels [and others]
Prentice-Hall, 2001
Buku Teks
Johnston, R.J. (Ronald John), author
Routledge, 2016
Buku Teks