AN INEQUALITY OF DUFFIN-SCHAEFFER-SCHUR TYPE. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 90, p. 109–123, 1998. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/289. Acesso em: 15 dec. 2025.