Porter, Gerald J.
Springer, 1996
Buku Teks
Leon, Steven J., author
Prentice-Hall, 1996
Buku Teks
White, Myron R.
Allyn and Bacon, inc., 1968
Buku Teks
Sofwah Ahmad, author
Universitas Indonesia, 2012
UI - Skripsi (Membership)
Hall, James E., author
Brooks/Cole, 1971
Buku Teks