Wacks, Raymond, author
Oxford University Press, 2013
Buku Teks
Easton, Susan M., author
Routledge, [date of publication not identified]
Buku Teks
Dacey, Austin, 1972-, author
Continuum, 2012
Buku Teks
Nash, Robert J., author
Jossey-Bass, 2008
Buku Teks
Lembaga Informasi Nasional, [date of publication not identified]
Buku Teks