Roman, Daniel D.
Prentice-Hall, 1968
Buku Teks
Francis, Philip H., author
AMACOM, 1977
Buku Teks
Howard, Keith, author
MCB University Press, 1990
Buku Referensi
White, P.A.F., author
Macmillan, 1975
Buku Teks
McLeod, T. S.
Gower Press, 1971
Buku Teks