Máté, A., and J. Szűcs. “On Measure-Theoretic Problems Involving Retrospective Sequential Functions”. Acta Cybernetica 1, no. 2 (January 1, 1971): 81-91. Accessed April 27, 2024. https://cyber.bibl.u-szeged.hu/index.php/actcybern/article/view/3076.