VLASENKO, L. A.; PIVEN’, A. L.; RUTKAS, A. G. Criteria for the Well-Posedness of the Cauchy Problem for Differential Operator Equations of Arbitrary Order. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 56, n. 11, p. 1484–1500, 2004. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3860. Acesso em: 16 feb. 2026.