?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=J+H&rft.au=Williams%2C+J+H&rft.aulast=Williams&rft.atitle=Light+interception+as+a+source+of+variation+for+nitrogen+fixation+in+groundnut+genotypes&rft.title=Plant+and+Soil&rft.issn=0032-079X&rft.date=1990&rft.volume=121&rft.pages=83-88&rft.issue=1&rft.genre=article