[1] Engestro, M.Y. (1987) Learning by expanding: An activity—Theoretical approach to developmental research. Orien-ta-Kunsultit, Helsinki.
[2] Mager, R.F. (1961) On the squencing of instructional content. Psychological Reports, 9, 405-413.
[3] Illeris, K. (2002) The three dimensions of learning: Contemporary learning theory in the tension field between the cognitive, the emotional and the social. NIACE, Leicester.
[4] Mezirow, J. (1991) Transformative dimensions of adult learning. Jossey-Bass, San Francisco.
[5] BoPED (2002) Bureau of planning and economic development report, in the Amhara regional state. Bahir Dar.
[6] UNECA (United Nations Economic Commission for Africa) (1996) Sustainable agriculture and environmental rehabilitation program (SAERP). Statistical Master book on sectoral conditions and activities, in the Amhara regional state.
[7] Gergen, K.J. (1994) Realities and relationships. Harvard University Press, Cambridge.