?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Koopmans%2C+Chris+J.&rft.aulast=Koopmans&rft.aufirst=Chris+J.&rft.date=2005&rft.title=NDICEA+as+a+user+friendly+model+tool+for+crop+rotation+planning+in+organic+farming&rft.genre=proceeding