?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=+Steinfeld+Ott%C3%B3&rft.aufirst=Ott%C3%B3&rft.aulast=Steinfeld&rft.issue=3-4&rft.atitle=%C3%9Cber+die+regul%C3%A4ren+duo-Elemente+in+Gruppoid-Verb%C3%A4nden&rft.title=Acta+scientiarum+mathematicarum&rft.volume=32&rft.pages=327-331&rft.issn=0001-6969&rft.date=1971&rft.genre=article