Simmonds, J.D., author
Columbia University Press, 1970
Buku Teks
Kaushik, Devendra
Sterling Publishers, , 1975
Buku Teks
Hinton, Harold C., author
Houghton Miffiln, 1966
Buku Teks
Barnett, A. Doak (Arthur Doak), author
Overseas Development Council, 1979
Buku Teks
edited by Ian Wilson
Angus and Robertson, 1973
Buku Teks