Short, John Rennie, author
Routledge, 1994
Buku Teks
Carlson, Lucile, author
Prentice-Hall, 1960
Buku Teks
De Blij, Harm J., author
John Wiley & Sons, 1967
Buku Teks
Barton, Jonathan R.
Routledge, 1997
Buku Teks
Flint, Colin, author
Routledge, Taylor & Francis Group, 2017
Buku Teks