Simmonds, J.D.
Columbia University Press, 1970
Buku Teks
Kit, Lau
[publisher not identified], [date of publication not identified]
Buku Teks
Kaushik, Devendra
Sterling Publishers, , 1975
Buku Teks
Hinton, Harold C.
Houghton Miffiln, 1966
Buku Teks
Barnett, Arthur Doak
Overseas Development Council, 1979
Buku Teks