Vlasenko, L. A., Piven’, A. L., & Rutkas, A. G. (2004). Criteria for the Well-Posedness of the Cauchy Problem for Differential Operator Equations of Arbitrary Order. Ukrains’kyi Matematychnyi Zhurnal, 56(11), 1484-1500. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/3860