LYSENKO, Z. M.; MATVIYUK, L. V.; NECHAEV, L. V.; SHVETS, V. T. On the fredholm theory of a planar problem with shift for a pair of functions. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 63, n. 4, p. 566–571, 2011. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2742. Acesso em: 5 dec. 2025.