?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=+Gr%C3%A4tzer+George+A.&rft.aulast=Gr%C3%A4tzer&rft.aufirst=George+A.&rft.volume=75&rft.issn=0001-6969&rft.title=Acta+scientiarum+mathematicarum&rft.pages=13-28&rft.atitle=Congruence-preserving+extensions+of+congruence-finite+lattices+to+isoform+lattices&rft.date=2009&rft.issue=1-2&rft.genre=article