King, Gareth, author
Routledge, 2005
Buku Teks
Trzeciak, John, author
Phoenix, 1997
Buku Teks
Hornby, Albert Sydney, author
Oxford University Press, 1977
Buku Referensi
Hornby, Albert Sydney, author
Oxford University Press,
Buku Referensi
Hornby, Albert Sydney, author
Oxford University Press, 1992
Buku Referensi