Ferris, Kenneth R.
Richard D. Irwin, 1989
Buku Teks
Ferris, Kenneth R.
Irwin, McGraw-Hill, 1996
Buku Teks SO
Gibson, Charles H.
South Western College , 2001
Buku Teks SO
Black, Geoff
London : Prentice-Hall, 2001,
Buku Referensi
Black, Geoff
Prentice-Hall, 2002
Buku Referensi