SYROVATSKY, A. N. The behavior of a discrete spectrum at a one-dimensional perturbation. Reports of the National Academy of Sciences of Ukraine, Kyiv, Ukraine, n. 5, p. 19–21, 2024. DOI: 10.15407/dopovidi2016.05.019. Disponível em: https://nasu-periodicals.org.ua/index.php/dp/article/view/10449. Acesso em: 23 dec. 2024.