Norton, Henry K.
Allen & Unwin , [date of publication not identified]
Buku Teks SO
Vandenbosch, Amry
University of Kentucky Press, 1957
Buku Teks SO
Fishers, David A.
West Publishing Company, 1994
Buku Teks
Asad-ul Iqbal Latif
ISEAS, 2007
Buku Teks SO
Australia EAAU 1996,
Buku Teks