An algorithmic proof theory for hypergeometric
(ordinary and "q") multisum/integral identities
by Herb Wilf and Doron Zeilberger.
Appeared in Invent. Math. 108 (1992), 575-633.
This is a WZ classic.
.ps version
.pdf version
Doron Zeilberger's List of Papers
Doron Zeilberger's Home Page