Bell, Judith
McGraw-Hill Education, 2014
Buku Teks
Goddard, Murray C.
Tab Books, 1977
Buku Teks
Beneficial Management Institute, [Date of publication not identified]
Buku Teks
Bell, Judith
Open University Press, 1993
Buku Teks
edited by Geoffrey Walford
Falmer Press, 1998
Buku Teks