?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=M+D&rft.au=Abdurahman%2C+M+D&rft.aulast=Abdurahman&rft.atitle=Nitrogen+returns+to+soil+by+selected+cropping+systems+on+a+Vertisol+in+the+semi-arid+tropics+of+India&rft.title=Crop+Research+(Hisar)&rft.issn=0970-4884&rft.date=1999&rft.volume=17&rft.pages=273-281&rft.issue=3&rft.genre=article