?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=Bruni%2C+Roberto&rft.aufirst=Roberto&rft.aulast=Bruni&rft.title=Scientific+Annals+in+Computer+Science&rft.volume=20&rft.issn=1843+-+8121&rft.pages=53-96&rft.date=2010&rft.atitle=An+Algebra+of+Hierarchical+Graphs+and+its+Application+to+Structural+Encoding&rft.genre=article