MACHNIAK, A. Polish military intelligence and counterintelligence activities against the Soviet Union 1918–1939: a description of operations from the files of the main directorate of information of the Polish army . Journal of Humanities and Social Sciences, [S. l.], v. 2, n. 1, p. 27–43, 2017. DOI: 10.15584/johass.2017.1.2. Disponível em: https://journals.ur.edu.pl/jhss/article/view/124. Acesso em: 12 nov. 2026.