?url_ver=Z39.88-2004&rft_id=10.1080%2F01904167.2013.799190&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=H&rft.au=Uchino%2C+H&rft.aulast=Uchino&rft.atitle=Calibrating+Chlorophyll+Meter+(Spad-502)+Reading+by+Specific+Leaf+Area+for+Estimating+Leaf+Nitrogen+Concentration+in+Sweet+Sorghum&rft.title=Journal+of+Plant+Nutrition&rft.issn=0190-4167&rft.date=2013&rft.volume=36&rft.pages=1640-1646&rft.issue=10&rft.genre=article