Callow, Duncan
Chischester, 1995
Buku Teks
Callow, Duncan
Otter Publications , 1995
Buku Teks
Carvan, J.C.
LBC Information Service, 1997
Buku Teks
Pritchard, John
Viking, 1992
Buku Referensi
general editor Michael Renshall
Butterworth, 1990
Buku Referensi