Pels, Dick.
Routledge, 1998
Buku Teks
Bainbridge, David, author
Pearson - Longman, 2002
Buku Teks
McJohn, Stephen M., 1959-, author
Wolters Kluwers, 2015
Buku Teks
Eastaway, Nigel, author
Sweet & Maxwell, 2008
Buku Teks
Matthew David, Debora Halbert, editors
SAGE Publications, 2015
Buku Teks