Kirkpatrick, Larry D., author
Thomson, Brooks, 2007
Buku Teks
Kirkpatrick, Larry D., author
Brooks/Cole Cengage Learning, 2010
Buku Teks
Buku Teks
edited by Sidney Mailick; The United Nations Institute for Training and Research
Anchor Press, 1974
Buku Teks
Simpson, George Gaylord, author
Harcourt Brace & World, 1964
Buku Teks