Brailford, Barry
A.H & A.W Reed , 1984
Buku Teks
Mulgan, Richard
Oxford University Press, 1989
Buku Teks
CP Books, [date of publication not identified]
Buku Teks
Gee, Maurice
Auckland University Press, 1975
Buku Teks
Mansfield, Katherine, author
Century Hutchinson, 1988
Buku Teks