Plant, Derrick, author
Zanichelli, 1978
Buku Teks
Lennie, Delia.
Longmans, 1960
Buku Teks
Speight, Kathleen, author
The English Universities Press, 1957
Buku Teks
Crowell, Thomas Lee, author
McGraw-Hill, 1987
Buku Referensi
Chiuchiu, Angelo, author
Guerra, 1990
Buku Teks