1. Delbecq A. \fcndelau A.H. & Gustafcon D.H. (1975). Group Techniques for Program Planning. Illinois: Scott Foresman Co. p. 19.
2. Kaufman RA. (1972). Educational System Planning. New Jersey: Prentice-Hall Inc. p. 23.
3. Knowles. M. (1980). The Modem Practice of Adult Education. Chicago: Folle« Publishing Company pp. 44-45 48-49 57-58 82 88 232.
4. United States Government Department of Health Education and Welfare (DHEW). (1979). The National Nursing Home Survey: 1977 Summary for the United States (DHEW) (PHS Publication Number 79-1794). Series B Number 43. Hyattsville Maryland: National Center for Health Statistics.