Shovkoplyas V. N.
Ukr. Mat. Zh. - 2000. - 52, № 6. - pp. 861–864
We obtain necessary and sufficient conditions for the solvability of a two-point boundary-value problem for systems of linear differential equations of the second order in the critical case where the corresponding homogeneous boundary-value problem has nontrivial solutions. We construct the general solution of the considered boundary-value problem.
Ukr. Mat. Zh. - 1979. - 31, № 5. - pp. 517–524