USTIMENKO, V. On walks of variable length in the Schubert incidence systems and multivariate flow ciphers . Reports of the National Academy of Sciences of Ukraine, Kyiv, Ukraine, n. 3, p. 55–63, 2025. DOI: 10.15407/dopovidi2014.03.055. Disponível em: https://nasu-periodicals.org.ua/index.php/dp/article/view/15617. Acesso em: 18 apr. 2026.