?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=M+V+K&rft.au=Sivakumar%2C+M+V+K&rft.aulast=Sivakumar&rft.date=1990&rft.title=Natural+Resources+Management+For+Sustainable+Agriculture+In+The+Sudano-Sahelian+Zone&rft.genre=proceeding