London; Cassell LTD., 1978
Buku Referensi
London, London Longmans
Buku Referensi
London, 1982
Buku Referensi
Beijing Waiyanshe (Foreign Language Teaching and Research Press) 2001
Buku Referensi
Wichman, K., author
New York, David Mckay Company
Buku Referensi