SHMARDA, Z. Existence and uniqueness of solution of the Cauchy problem for singular systems of integro-differential equations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 45, n. 12, p. 1716–1720, 1993. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5983. Acesso em: 5 dec. 2025.