?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Oehen%2C+Bernadette&rft.aulast=Oehen&rft.aufirst=Bernadette&rft.date=January+2007&rft.title=Co-existence+in+maize+supply+chains+in+Spain+and+Switzerland&rft.genre=proceeding