Bell, Judith
McGraw-Hill Education, 2014
Buku Teks
Goddard, Murray C.
Tab Books, 1977
Buku Teks
Bell, Judith
Open University Press, 1993
Buku Teks
Beneficial Management Institute, [Date of publication not identified]
Buku Teks
Molly Andrews, Corinne Squire, Maria Tamboukou, editor
Sage, 2009
Buku Teks