V. A. Litovchenko, “Cauchy problem for one class of pseudodifferential systems with entire analytic symbols”, Ukr. Mat. Zhurn., vol. 58, no. 9, pp. 1211–1233, Sep. 2006, Accessed: Apr. 09, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/3523