?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=G+D&rft.au=Smith%2C+G+D&rft.aulast=Smith&rft.date=1990&rft.title=Managing+Soil+Structure+Under+Rainfed+Conditions&rft.genre=proceeding