Delair Publishing Company, 1981
Buku Referensi
Halderman, James D., author
2006
Multimedia
Hewings, Martin, author
Cambridge University Press, 2005
Buku Teks
Doff, Adrian, author
Cambridge University Press , 2011
Buku Teks
Hornby, Albert Sydney, author
Oxford University Press, 1977
Buku Referensi