GRĄDZKA, E. A companion to Kazimierz Twardowski. Philosophical Problems in Science (Zagadnienia Filozoficzne w Nauce), [S. l.], n. 72, p. 191–202, 2022. DOI: 10.59203/zfn.72.586. Disponível em: https://www.zfn.edu.pl/index.php/zfn/article/view/586. Acesso em: 7 sep. 2025.