Black, Michael, author
Cambridge University Press, 2008
Buku Teks
Hornby, Albert Sydney, author
Oxford University Press, 1991
Buku Referensi
Hornby, Albert Sydney, author
Oxford University Press , 1963
Buku Teks
[publisher not identified], [date of publication not identified]
Buku Referensi
Hornby, Albert Sydney, author
Oxford University Press, 1973
Buku Referensi