?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Groot%2C+S.P.C.&rft.aulast=Groot&rft.aufirst=S.P.C.&rft.date=2006&rft.title=Improvement+of+the+quality+of+propagation+material+for+organic+farming+system&rft.genre=proceeding