ODINTSOV, S. P. “Reductio ad absurdum” and Łukasiewicz’s modalities. Logic and Logical Philosophy, [S. l.], n. 11-12, p. 149–166, 2003. DOI: 10.12775/LLP.2003.008. Disponível em: https://apcz.umk.pl/LLP/article/view/LLP.2003.008. Acesso em: 17 jan. 2022.