?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&rft.au=Velik%2C+Margit&rft.aulast=Velik&rft.aufirst=Margit&rft.date=2006&rft.title=Partial+substitution+of+concentrates+by+maize+silage+in+rations+for+organic+dairy+cows+and+its+influence+on+performance+and+utilization+efficiency&rft.genre=proceeding