Pietruszczak, Andrzej. “Some Additional Axioms for T-Normal Logics. Defining K45, KB4, KD45 and S5 Without Using Modal Rules”. Bulletin of the Section of Logic (June 24, 2024): 23 pp. Accessed July 22, 2024. https://czasopisma.uni.lodz.pl/bulletin/article/view/22813.