LOPOTKO, O. V. Integral representation of even positive-definite functions of two variables. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 6, p. 844–853, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2768. Acesso em: 5 dec. 2025.