?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Walker%2C+T+S&rft.aufirst=T+S&rft.aulast=Walker&rft.isbn=9781780644011&rft.tpages=478&rft.date=2015&rft.title=Varietal+Adoption%2C+Outcomes+and+Impact&rft.btitle=Crop+Improvement%2C+Adoption+and+Impact+of+Improved+Varieties+in+Food+Crops+in+Sub-Saharan+Africa&rft.genre=bookitem