Artikel Jurnal
edited by Harold M. Groves
Henry Holt and Company, 1955
Buku Teks
Buck, A. E., author
Public Administration Service, 1949
Buku Teks
McDaniels, John F., author
The World Community Association, 1964
Buku Teks
Stoessinger, John G., author
Brookings Institution, 1964
Buku Teks