Trevaskis, G. A. An evaluation of the extension manual of the Department of Agriculture, Stock and Fisheries / prepared Dr. G.A. Trevaskis. - [Waigani, Port Moresby] : Educational Materials Centre, U.P.N.G., 1969. - 48 leaves, - Research report ; 2 . Subjects--Topical Terms: Agricultural extension work--Papua New Guinea.