Muravitsky, Alexei Y. “The Contribution of A.V. Kuznetsov to the Theory of Modal Systems and Structures”. Logic and Logical Philosophy 17, no. 1-2 (June 19, 2008): 41–58. Accessed April 26, 2024. https://apcz.umk.pl/LLP/article/view/LLP.2008.004.