Steingass, F.
New Delhi : Gaurav Publishing House, 1986,
Buku Referensi
Cambridge University Press, 2005
Buku Referensi
Sutanto Atmosumarto, author
Atma Stanton, 2004
Buku Referensi
Hornby, Albert Sydney, author
Oxford University Press , 1963
Buku Teks
Hornby, Albert Sydney, author
Oxford University Press, 1973
Buku Referensi