Il’kivV. S., & StrapN. I. (2015). Solvability of the Nonlocal Boundary-Value Problem for a System of Differential-Operator Equations in the Sobolev Scale of Spaces and in a Refined Scale. Ukrains’kyi Matematychnyi Zhurnal, 67(5), 611-624. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/2009