Mickelburgh, John
Profesional Books, 1979
Buku Teks
Cartwright, Peter, author
Cambridge, 2001
Buku Teks
Morgan, Richard, author
Sweet & Maxwell, 2012
Buku Teks
Jay, Rosemary, author
Sweet & Maxwell , 2012
Buku Teks
London : Consumers association and hodder & stoughton, 1989, 1989
Buku Referensi