Cohen, Monique, author
Sage, 2000
Buku Referensi
McLeod, John, author
McGraw-hill Open University press, 2012
Buku Teks
Paylor, Ian, author
McGraw-Hill, 2012
Buku Teks
Nelson-Jones, Richard, author
Sage Publications, 2004
Buku Teks
Nelson-Jones, Richard, author
Thousand Oaks, California: SAGE, 2014
Buku Teks