1. Adams, James Luther. 1976. On Being Human Religiously. Boston: Beacon.
2. Anderson, Robert T. 1973. “Voluntary Associations in History: From Paleolithic to Present Times.” Pp. 9–28 in David Horton Smith (ed.). Voluntary Action Research. Lexington, MA: Heath/Lexington Books.
3. Barash, David P. 1977. Sociobiology and Behavior. New York: Elsevier.
4. Beveridge, Lord W. 1948. Voluntary Action. London: Allen and Linwin.
5. Commission on Private Philanthropy and Public Needs. 1975. Giving in America: Toward a Stronger Voluntary Sector. Washington, D.C.