?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=+Mukhopadhyay+S.+N.&rft.aufirst=S.+N.&rft.aulast=Mukhopadhyay&rft.title=Acta+scientiarum+mathematicarum&rft.issue=3-4&rft.date=1972&rft.pages=207-210&rft.issn=0001-6969&rft.volume=33&rft.atitle=On+a+property+of+approximate+derivatives&rft.genre=article