Gleeck, Lewis E.
Historical Conservation Society, 1976
Buku Teks
Berry, William E.
Westview Press, 1989
Buku Teks
University of Queensland Press, 1973
Buku Teks
Wilson, James Q., author
D.C. Heath, 1995
Buku Teks
Wilson, James Q., author
D.C. Helath and Co., 1986
Buku Teks