?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=+Drewes+Frank&rft.aufirst=Frank&rft.aulast=Drewes&rft.title=Acta+cybernetica&rft.atitle=MAT+learners+for+recognizable+tree+languages+and+tree+series&rft.pages=249-274&rft.date=2009&rft.issue=2&rft.volume=19&rft.issn=0324-721X&rft.genre=article