Matthews, Joseph R.
Libraries Unlimited, 2004
Buku Teks
Harmon, Roy L.
Free Press, 1996
Buku Teks
Ashby, Eric
Stanford University Press, 1978
Buku Teks
Beekman, George
Pretince Hall, 2002
Buku Teks
Record, Matthew
Glorier International, 1999
Buku Referensi