Pietruszczak, Andrzej. β€œOn Theses Without Iterated Modalities of Modal Logics Between C1 and S5. Part 1”. Bulletin of the Section of Logic 46, no. 1/2 (June 30, 2017): 111–133. Accessed December 17, 2025. https://czasopisma.uni.lodz.pl/bulletin/article/view/2933.