?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.aufirst=Birte&rft.au=Boelt%2C+Birte&rft.aulast=Boelt&rft.title=Co-existence+of+genetically+modified+crops+with+conventional+and+organic+crops&rft.date=2003&rft.genre=proceeding