Developing technology with farmers : a trainer's guide for participatory learning / Veldhuizen, Laurens van Veldhuizen, Laurens van Waters-Bayer, Ann Zeeuw, Henk de Agricultural extension workers Farmers Agricultural extension work Agriculture 630 ZED 1997 C160 Or. London ; New York : Zed Books in association with ETC Netherlands BV, Leusden, 1997 1997 Text ix, 230 p. :