ยง A = B --- A book about proofs of combinatorial closed forms

The book explains algorithms on solving closed forms for combinatorial recurrences, by means of Zeilberger's algorithm. The book is written by Zeilberger himself, and supposedy also teaches one Maple. I'd like to learn the algorithm, since it might be useful eventually for Groebner basis / loop analysis shenanigans I like to play as part of my work on compilers.