DETERMINATION OF THE FORCE FUNCTION FROM A GIVEN INTEGRAL OF THE EQUATION OF MOTION ArticleGALIULLIN A.S.Differential Equations. Том 18. 1982. С. 530-532
INEQUALITIES FOR VALUES OF DIFFERENTIAL-OPERATORS ON ALGEBRAIC POLYNOMIALS ON A SPHERE ArticleZHIDKOV G.V.Differential Equations. Том 17. 1981. С. 329-336