Baron, Robert A., author
Allyn and Bacon, 1991
Buku Teks
Villiers, Peter
Cipta Manunggal, 1999
Buku Teks
Wilson, George P., author
F.S. Crofts, 1947
Buku Teks
Burt, Angela, author
Stanley Thornes, 1995
Buku Referensi
Bodinski, Louis H., author
John Wiley & Sons, 1987
Buku Teks