Jackson, W.A. Douglas, author
John Wiley & Sons, 1985
Buku Teks
Spencer, J.E., author
John Wiley & Sons, 1969
Buku Teks
Crang, Mike, author
Routledge, 1998
Buku Teks
[publisher not identified], [date of publication no identified]
Buku Teks
Malinowski, Jon C., author
McGraw-Hill, 2012
Buku Teks