BERNGARDT, O.; VORONOV, A. A least squares method for sums of functions satisfying the differential equations with polynomial coefficients. Numerical Methods and Programming (Vychislitel’nye Metody i Programmirovanie), [S. l.], v. 4, n. 4, p. 167–171, 2003. Disponível em: https://en.num-meth.ru/index.php/journal/article/view/85. Acesso em: 24 apr. 2024.