Google Scholar has identified 2.071 citations for publications as of December 31, 2011. Cluster Ensemble work clearly being the most popular.
Citations Top 10 December 31, 2011
Citations Timeline December 31, 2011
Each following line contains the PhD advisor. Lines are indented only if more
than one advisor exists. May appear impressive, but the mathematical circles were much smaller and closely knit in the mid1800s and earlier.

Alexander Strehl,
University of Texas at Austin, 2002

Joydeep
Ghosh
,
University of Southern California, 1988

Kai Hwang
, University of California, Berkeley, 1972

Arthur Gill
, University of California,
Berkeley, 1959

Aram John
Thomasian, University of
California, Berkeley, 1956

David Harold Blackwell, University of
Illinois at UrbanaChampaign, 1941

Joseph Leo
Doob,
Harvard University, 1932

Joseph Leonard Walsh, Harvard
University, 1920

Advisor 1:
Maxime
Bôcher,
GeorgAugustUniversität Göttingen, 1891

Advisor 2:
George David
Birkhoff
,
The University of Chicago, 1907
The Erdős number describes the "collaborative distance" between a person and mathematician Paul Erdős, as measured by authorship of mathematical papers. It was surprising to find a path to Erdős. However, 4 is only slightly below median amongst those who have finite Erdős numbers.
Paul Erdős
 Frank Harary (with Erdős in 1980  Residuallycomplete graphs)
 Miroslaw Malek (with Harary in 1990  Quantifying fault recovery in multiprocessor systems)
 J. K. Aggarwal (with Malek in 1984  Workstations in a Local Area Network Environment)
 Alexander Strehl (with Aggarwal in 2000  MODEEP: a motionbased object detection and pose estimation method for airborne FLIR sequences)