On the a. e. convergence of $T^nf/a_n$ in $L_1$- space. (English). In: Frolík, Z., Souček, V. and Vinárek, J. (eds.): Proceedings of the 13th Winter School on Abstract Analysis. Section of Analysis. Circolo Matematico di Palermo, Palermo, 1985. pp. [57]-61