1. F. Hartman and G. Stampacchia, “On some non-linear elliptic differential-functional equations,” Acta Math. 115, 271–310 (1966).
2. A. B. Antonevich, “The index and the normal solvability of a general elliptic boundary-value problem with a finite group of shifts on the boundary,” Differ. Uravn. 8 (2), 309–317 (1972).
3. V. S. Rabinovich, “On the solvability of differential-difference equations on Rn and in the half-space,” Dokl. Akad. Nauk SSSR 243 (5), 1134–1137 (1978).
4. G. G. Onanov and A. L. Skubachevskii, “Nonlocal problems in the mechanics of the three-layer shells,” Math. Model. Nat. Phenom. 12 (6), 192–207 (2017).
5. G. G. Onanov and E. L. Tsvetkov, “On the mininum of the energy functional with respect to functions with deviating argument in a stationary problem of elasticity theory,” Russ. J. Math. Phys. 3 (4), 491–500 (1995).