[1]
L. I. Komarnyts'ka and B. I. Ptashnik, “Boundary-value problems for differential equations unsolvable with respect to the higher time derivative”, Ukr. Mat. Zhurn., vol. 47, no. 9, pp. 1197–1208, Sep. 1995, Accessed: Dec. 06, 2025. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5519