II`INSKII, A. A theorem on stability of the argument of characteristic function. Математическая физика, анализ, геометрия, Харків, Україна, v. 3, n. 1-2, p. 70–79, 1996. Disponível em: http://mag.ilt.kharkiv.ua/index.php/mag/article/view/m03-0070e. Acesso em: 20 трав. 2024.