Abrahamson, Mark, author
Cambridge University Press, 2014
Buku Teks
Clark, David, 1946-, author
Routledge, 1996
Buku Teks
David Vlahov, author
Jossey-Bass, 2010
Buku Teks
Knox, Paul, author
Longman, 1996
Buku Teks
Alfed, Louis Edward, author
Wright-Allen Press, 1976
Buku Teks