?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Hopkins%2C+Alan&rft.aulast=Hopkins&rft.aufirst=Alan&rft.date=2002&rft.title=Multi-functional+roles+of+grassland+in+organic+farming+systems+&rft.genre=proceeding