COMĂNECI, Andrei. On Fryszkowski’s problem. Studia Universitatis Babeș-Bolyai Mathematica, [S. l.], v. 62, n. 4, p. 537–542, 2017. DOI: 10.24193/subbmath.2017.4.10. Disponível em: https://studia.reviste.ubbcluj.ro/index.php/subbmathematica/article/view/1919. Acesso em: 5 feb. 2025.