Baugh, W.E.
MacMillan Press, 1977
Buku Teks
Jones, Andrew
Longman Australia, 1992
Buku Teks
Sigit Wijayanta
Yakkum , 2002
Buku Teks
Friedlander, Walter A., author
Prentice Hall of India, 1982
Buku Teks
Friedlander, Walter A., author
Prentice-Hall, 1968
Buku Teks