Byrt, W.J.
McGraw-Hill Book, 1972
Buku Teks
edited by Samir Mankabady
Croom Helm, 1984
Buku Teks
Lawlor, Alan
Macmillan Press , 1973
Buku Teks
edited by Paul Taylor and A.J.R. Groom
Frances Pinter, 1978
Buku Teks
Kenley, W.J.
Butterworth, 1984
Buku Teks