1. Abramov, S.A.: Applicability of Zeilberger’s algorithm to hypergeometric terms. In: Proceedings of ISSAC 02, pp. 1–7. ACM Press, New York (2002).
2. Abramov, S.A., Le, H.Q.: Applicability of Zeilberger’s algorithm to rational functions. In: Proceedings FPSAC’2000, pp. 91–102. Springer LNCS (2000).
3. Apagodu, M., Zeilberger, D.: Multi-variable Zeilberger and Almkvist-Zeilberger algorithms and the sharpening of Wilf-Zeilberger theory. Adv. Appl. Math. 37, 139–152 (2006)
4. Apéry, R.: Irrationalité de
$$\zeta (2)$$
ζ
(
2
)
et
$$\zeta (3)$$
ζ
(
3
)
. Astérisque 61, 11–13 (1979)
5. Askey, R.: Dual equations and classical orthogonal polynomials. J. Math. Anal. Appl. 24, 677–685 (1968)