EFTEKHARINASAB, K. A multiplicity theorem for Fréchet spaces. Reports of the National Academy of Sciences of Ukraine, Kyiv, Ukraine, n. 5, p. 10–15, 2022. DOI: 10.15407/dopovidi2022.05.010. Disponível em: https://nasu-periodicals.org.ua/index.php/dp/article/view/2022-5-2. Acesso em: 29 may. 2025.