?url_ver=Z39.88-2004&rft_id=doi%3A10.1007%2Fs11004-011-9325-x&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=Pei%2C+Tao&rft.aulast=Pei&rft.aufirst=Tao&rft.issue=3&rft.volume=43&rft.date=April+2011&rft.issn=1874-8961&rft.atitle=A+Nonparametric+Index+for+Determining+the+Numbers+of+Events+in+Clusters&rft.title=Mathematical+Geosciences&rft.pages=345-362&rft.genre=article