Appeard in J. Combinatorial Theory (ser. A) 66 (1994), 17-27.
My consolation prize for being beaten by George Andrews in the race to prove the TSSCPP conjecture.
Note Added Aug. 2, 1999: This is the original uncensored version, containing an epilogue that was not published in the published version that appeared in JCT(A), following a request of George Andrews, who was the editor that was in charge.
Another Note: Christian Krathenthaler has proved all the conjectures in this article, but failed to earn the prize, since he "cheated" and used the determinant-evaluation methodology rather than the constant-term methodlogy.
Doron Zeilberger's List of Papers