SHAPIRO, B. Root Asymptotics for the Eigenfunctions of Univariate Differential Operators. Acta Polytechnica, Prague, Czech Republic, v. 50, n. 5, 2010. DOI: 10.14311/1275. Disponível em: https://ojs.cvut.cz/ojs/index.php/ap/article/view/1275. Acesso em: 2 apr. 2025.