POLAK, P. J. Virtual entities – a part of our reality. Philosophical Problems in Science (Zagadnienia Filozoficzne w Nauce), [S. l.], n. 68, p. 306–310, 2020. Disponível em: https://www.zfn.edu.pl/index.php/zfn/article/view/521. Acesso em: 6 may. 2025.