Łyczak, Marcin, and Andrzej Pietruszczak. “On the Definability of Leśniewski’s Copula ‘is’ in Some Ontology-Like Theories”. Bulletin of the Section of Logic 47, no. 4 (December 30, 2018): 233–263. Accessed May 18, 2024. https://www.czasopisma.uni.lodz.pl/bulletin/article/view/4776.