English, Jack
McGraw-Hill, 1992
Buku Teks
Smart, Huw
Oxford University Press, 2006
Buku Referensi
edited by George A. Hawkins
McGraw-Hill, 1968
Buku Teks
cordinating editor, Geoge A. Hawkins
McGraw-Hill, 1968
Buku Teks
Smart, Huw
Oxford University Press, 2006
Buku Referensi