Kaplan, Robert D., author
Caroline Cunningham, 2000
Buku Teks
editor, E. Dale Cluff
The Haworth Press , 1990
Buku Teks
Artikel Jurnal
Parkinson, Brian, 1958-
Routledge, 1995
Buku Teks
edited by Franklin D. Margiotta, James Brown, and Michael J. Collins
Westview Press, 1983
Buku Teks