1988: Extension is a professional communication intervention deployed by an institution to induce change in voluntary behaviours with a presumed public or collective utility.[7]
1999: The essence of agricultural extension is to facilitate interplay and nurture synergies within a total information system involving agricultural research, agricultural education and a vast complex of information-providing businesses.[9]
2004: Extension [is] a series of embedded communicative interventions that are meant, among others, to develop and/or induce innovations which supposedly help to resolve (usually multi-actor) problematic situations.[10]
^Brunner, E. and Hsin Pao Yang, E. (1949) Rural America and the Extension Service, Columbia University
^Saville, A.H. (1965) Extension in Rural Communities: A Manual for Agricltural and Home Extension technician Workers. Oxford University Press
^Bradfield, D.J. (1966) Guide to Extension Training (1st Edition), FAO
^Maunder, A. (1973) Agricultural Extension: A Reference Manual (1st Edition), FAO
^van den Ban, A. (1974) Inleiding tot de Voorlichtingskunde, (Dutch edition first published by Boom, later quoted in English editions: 1988, van den Ban and Hawkins, and 2004, Leeuwis and van den Ban)
^Adams, M. (1982) Agricultural Extension in Developing Countries, Longman
^Roling, N. (1988) Extension Science: Information Systems in Agricultural Development, Cambridge University Press
^Nagel, U. J. (1997) Alternative Approaches to Organizing Extension, in Swanson, B. “Improving Agricultural Extension: A Reference Manual" (3rd Edition)” FAO
^Neuchatel Group,(1999) Common Framework on Agricultural Extension
^Leeuwis, C. and van den Ban, A. Communication for Rural Innovation: Rethinking Agricultural Extension (3rd Edition), Blackwell Publishing
^Trager, J. (1996) The Food Chronology, Aurum Press, London
^Jones, G.E. and Garforth, C. (1997) The history, development, and future of agricultural extension in Swanson, B. “Improving Agricultural Extension: A Reference Manual (3rd Edition)” FAO
^NAFES (2005) Consolidating Extension in the Lao PDR, National Agricultural and Forestry Extension Service, Vientiane