Kingma, Bruce R.
Libraries Unlimited, Inc., 1996
Buku Teks
Henczel, Susan
Saur Verlag, 2001
Buku Teks SO
Dick, Archie L.
Unisa Press, 2002
Buku Teks SO
Wolman, Yecheskel
John Wiley & Sons, 1983
Buku Teks SO
Castells, Manuel
Blackwell, 1998
Buku Teks SO