Bressoud, D. Proofs and Confirmations: The Story of the Alternating Sign Matrix Conjecture. Cambridge, England: Cambridge University Press, 1999.Bressoud, D. and Propp, J. "How the Alternating Sign Matrix Conjecture was Solved." Not. Amer. Math. Soc.46, 637-646.Finch, S. R. Mathematical Constants. Cambridge, England: Cambridge University Press, p. 413, 2003.Kuperberg, G. "Another Proof of the Alternating-Sign Matrix Conjecture." Internat. Math. Res. Notes, No. 3, 139-150, 1996.Zeilberger, D. "A Constant Term Identity Featuring the Ubiquitous (and Mysterious) Andrews-Mills-Robbins-Rumsey numbers 1, 2, 7, 42, 429, ...." J. Combin. Theory A66, 17-27, 1994.Zeilberger, D. "Proof of the Alternating Sign Matrix Conjecture." Electronic J. Combinatorics3, No. 2, R13, 1-84, 1996a. http://www.combinatorics.org/Volume_3/Abstracts/v3i2r13.html.Zeilberger, D. "Proof of the Refined Alternating Sign Matrix Conjecture." New York J. Math.2, 59-68, 1996b.