Abel, N. H. "Beweis eines Ausdrucks, von welchem die Binomial-Formel ein einzelner Fall ist." J. reine angew. Math.1, 159-160, 1826. Reprinted in Œuvres Complètes, 2nd ed., Vol. 1. pp. 102-103, 1881.Bhatnagar, G. Inverse Relations, Generalized Bibasic Series, and their U(n) Extensions. Ph.D. thesis. Ohio State University, p. 61, 1995.Comtet, L. Advanced Combinatorics: The Art of Finite and Infinite Expansions, rev. enl. ed. Dordrecht, Netherlands: Reidel, p. 128, 1974.Ekhad, S. B. 和 Majewicz, J. E. "A Short WZ-Style Proof of Abel's Identity." Electronic J. Combinatorics3, No. 2, R16, 1, 1996. http://www.combinatorics.org/Volume_3/Abstracts/v3i2r16.html.Foata, D. "Enumerating -Trees." Discr. Math.1, 181-186, 1971.Riordan, J. Combinatorial Identities. New York: Wiley, p. 18, 1979.Roman, S. "The Abel Polynomials." §4.1.5 in The Umbral Calculus. New York: Academic Press, pp. 29-30 and 72-75, 1984.Saslaw, W. C. "Some Properties of a Statistical Distribution Function for Galaxy Clustering." Astrophys. J.341, 588-598, 1989.Strehl, V. "Binomial Sums and Identities." Maple Technical Newsletter10, 37-49, 1993.Strehl, V. "Binomial Identities--Combinatorial and Algorithmic Aspects." Discrete Math.136, 309-346, 1994.