Hutheesing, Raja
Orient Longmans,, 1960
Buku Teks
Saw, Ron
Richard Griffin, 1984
Buku Teks
Kemp, Patrick S.
Dow Jones-Irwin, Inc., 1970
Buku Teks
Patrick, Daniel
Harvard University Press, 1990
Buku Teks
Geddes, Patrick
Williams & Norgate, 1949
Buku Teks