Seymour, Daniel T.
Oryx Press , 1993
Buku Teks
Schlossberg, Nancy K.
Jossey-Bass Publishers, 1989
Buku Teks
John C. Smart
Springer, 2012
eBooks
Hiam, Alexander, author
Prentice-Hall, 1992
Buku Teks
Lewis, Ralph G., author
St. Lucie Press, 1994
Buku Teks