Wright, Richard T.
Pearson Education, 2002
Buku Teks
Honachefsky, William B., author
Noyes Pub., 1991
Buku Referensi
Harvey, L.D. Danny, author
Prentice-Hall, 2000
Buku Teks
edited by Howard Frumkin
Jossey-Bass, 2010
Buku Teks
Kemp, David D., author
Routledge , 1994
Buku Teks