L. I. Zagulyaeva, “Conditions for the solvability of a certain boundary value problem for a system of differential equations”, Differ. Uravn., 8:5 (1972), 774–777
2.
L. I. Zagulyaeva, “Conditions for the existence of a solution of a certain multipoint boundary value problem for a system of differential equations”, Differ. Uravn., 8:4 (1972), 725–726
