by Arthur J. Keown, John D. Martin, J. William Petty, and David F. Scott
Prentice-Hall, 2005
Buku Teks
Asch, David, author
Crest Publishing House, 1999
Buku Referensi
Block, Stanley B., author
Irwin, 1994
Buku Teks
Shapiro, Alan C., author
Allyn and Bacon, 1991
Buku Teks
Shapiro, Alan C., author
[Publisher not identified], [Date of publication not identified]
Buku Teks