Il’kiv V. S., Strap N. I. and Volyanska I. I. (2020) “Solvability conditions of a nonlocal boundary value problem for a differential-operator equation with nonlinearity in a refined Sobolev scale of spaces of functions of several real variables”, Ukrains’kyi Matematychnyi Zhurnal, 72(4), pp. 452-466. doi: 10.37863/umzh.v72i4.2270.