LAVRENT'EV, A. S.; MISHURA, Yu. S. The problem of extension for two-parameter kernels. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 49, n. 9, p. 1206–1212, 1997. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5119. Acesso em: 5 dec. 2025.