V. M. Prokip, “On the solvability of the Riccati matrix algebraic equation”, Ukr. Mat. Zhurn., vol. 46, no. 11, pp. 1591–1593, Nov. 1994, Accessed: Dec. 15, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5602