Odintsov, Sergei P., Daniel Skurt, and Heinrich Wansing. “On Definability of Connectives and Modal Logics over FDE”. Logic and Logical Philosophy 28, no. 4 (April 11, 2019): 631–659. Accessed April 19, 2024. https://apcz.umk.pl/LLP/article/view/LLP.2019.010.