Day, A. Colin, author
Oxford University Press , 1990
Buku Teks
Headington, Mark R., author
Jones and Bartlett Publisher, 1997
Buku Teks
McCracken, Daniel D., author
John Wiley & Sons, 1974
Buku Referensi
Schildt, Herbert, author
McGraw-Hill, 2001
Buku Teks
Pagan, Frank G., author
John Wiley & Sons, 1976
Buku Teks