1. V. V. Meleshko, Biharmonic Problems of Mechanics (Kiev State Univ., Kiev, 2011) [in Ukrainian].
2. W. Nowacki, Elasticity Theory (Mir, Moscow, 1975) [in Russian].
3. B. E. Pobedrya and D. V. Georgievskii, Lections on Elasticity Theory (Editorial URSS, Moscow, 1999) [in Russian].
4. I. N. Vekua, New Methods of Solving Elliptic Equations (GITTL, Moscow, 1948) [in Russian].
5. S. L. Sobolev, Introductory Theory of Cubature Formulas (Nauka, Moscow, 1974) [in Russian].