@INBOOK {AYANABA:1977c, title = {Manpower Needs for Soil Fertility Maintainance in the Developing Nations}, author = {Ayanaba, A. }, year = {1977}, type = {In Stanton, W.R. and Da Silva, E.J., eds . GIAM. State of the Art 1976 and its impact on Developing Countries}, publisher = {University of Malaya Press}, address = {Kuala Lumpur}, }