GRABOVA, U. Z. Approximation of the classes of convolutions of periodic functions by Zygmund sums in integral metrics . Reports of the National Academy of Sciences of Ukraine, Kyiv, Ukraine, n. 9, p. 13–18, 2025. DOI: 10.15407/dopovidi2014.09.013. Disponível em: https://nasu-periodicals.org.ua/index.php/dp/article/view/16677. Acesso em: 18 apr. 2026.