T. N. Zinchenko and A. A. Murach, “Douglis-Nirenberg elliptic systems in Hörmander spaces”, Ukr. Mat. Zhurn., vol. 64, no. 11, pp. 1477–1476, Nov. 2012, Accessed: Feb. 16, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/2674