Aderson, Nels
Free Press of Glencoe , 1961
Buku Teks
Herman, Harold
International City Managers Association, 1968
Buku Teks
Grundy, Fred, author
HK Lewis, 1974
Buku Teks
edited by Joseph S. Chen
Emerald, 2017
eBooks
Hoggarth, Elizabeth A
Avebury, 1991
Buku Teks