Gedam, Ratnakar M
Deep & Deep Publications, 1987
Buku Teks
Lesourne, Jacques
Englewood Cliffs, N.J., Prentice-Hall
Buku Teks
Flanagan, Robert J.
Scott, Foresman, 1984
Buku Teks
Nourse, Hugh O., author
McGraw-Hill, 1968
Buku Teks
Cambridge University Press, 1996
Buku Teks