1. [1] Appell, P. and Kampé de Fériet, J., Fonctions hypergéometriques et hypersphériques—Polynomes d'Hérmite, Gauthiers-Villars, 1926.
2. [2] Haraoka, Y., Irreducibility of accessory parameter free systems, Kumamoto J. Math., 8 (1995), 153-170.
3. [3] Kaneko, J., Monodromy group of Appell's system (F4), Tokyo J. Math., 4 (1981), 35-54.
4. [4] Kato, M., The Riemann problem for Appell's F4, Mem. Fac. Sci. Kyushu Univ. Ser. A, 47 (1993), 227-243.
5. [5] Kato, M., Connection formulas for Appell's system F4 and some applications, Funkcial. Ekvac., 38 (1995), 243-266.