McDowell, Ian
Oxford University Press, 1987
Buku Teks
McDowell, Ian
Oxford University Press, 1996
Buku Teks
Peterson, Robert A., author
Sage Publications, Inc., 2000
Buku Teks
Foddy, William, author
Cambridge University Press, 1993
Buku Teks
Streiner, David L., author
Oxford University Press, 2015
Buku Teks