Higher regularity of weak solutions of strongly nonlinear elliptic equations. (English). In: Vosmanský, Jaromír and Zlámal, Miloš (eds.): Equadiff 6. Proceedings of the International Conference on Differential Equations and Their Applications held in Brno, Czechoslovakia, Aug. 26 - 30, 1985. J. E. Purkyně University, Department of Mathematics, Brno, 1986. pp. [243]-246