Ronto AM. Exact Solvability Conditions for the Cauchy Problem for Systems of First-Order Linear Functional-Differential Equations Determined by $(σ_1, σ_2, . , σ_n; τ)$-Positive Operators. Ukr. Mat. Zhurn. [Internet]. 2003Nov.25 [cited 2024Jul.27];55(11):1541-68. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/4023