William J. Hardcastle, John Laver, Fiona E. Gibbon, editor
Wiley-Blackweell, 2013
Buku Teks
Thampan, Palakasseril Kumaran
Oxford & IBH Publishing Co., 1981
Buku Referensi
Prentice-Hall, 1991
Buku Referensi
Frederick S. Merritt and Jonathan T. Ricketts, editor
McGraw-Hill, Inc, 1994
Buku Referensi
edited by Linn C. Stuckenbruck
Addison-Wesley, 1981
Buku Referensi