Gilbert, Bentley B.
B.T. Bastford, Ltd., 1970
Buku Teks
Sullivan, Michael, author
Harvester Wheatsheaf, 1994
Buku Teks
Routledge, 1998
Buku Teks
Gregg, Pauline, author
George G. Harrap, 1967
Buku Teks
Cullingworth, J.B., author
Allen & Unwin, 1973
Buku Teks