?url_ver=Z39.88-2004&rft_id=doi%3A+10.1111%2Fj.1096-0031.2002.tb00160.x&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aulast=Gattei&rft.aufirst=Stefano&rft.au=Gattei%2C+Stefano&rft.volume=18&rft.title=Cladistics&rft.atitle=The+Positive+Power+of+Negative+Thinking&rft.date=2002&rft.pages=446-452&rft.issue=4&rft.genre=article