POLCYN, J.; GAWRYSIAK, M. Education Index and Level of Social Development as a Background for Examination Results on the Lower and Upper Level of Secondary School. Przegląd Badań Edukacyjnych (Educational Studies Review), [S. l.], v. 2, n. 23, p. 25–44, 2017. DOI: 10.12775/PBE.2016.071. Disponível em: https://apcz.umk.pl/PBE/article/view/PBE.2016.071. Acesso em: 25 apr. 2024.