MAKAROV, V. L. Sufficient conditions for the convergence of the V. A. Marchenko asymptotic series for eigenvalues of the Sturm–Liouville problem . Reports of the National Academy of Sciences of Ukraine, Kyiv, Ukraine, n. 11, p. 16–21, 2025. DOI: 10.15407/dopovidi2014.11.016. Disponível em: https://nasu-periodicals.org.ua/index.php/dp/article/view/16814. Acesso em: 12 apr. 2025.