Nicholson, Margaret, author
Oxford University Press, 1957
Buku Referensi
Heinle & Heinle, 1996
Buku Referensi
McGraw-Hill, 1956
Buku Teks
Tilbury, Alex, author
Cambridge University Press, 2011
Multimedia
Clementson, Theresa, author
Cambridge University Press, 2011
Multimedia