DETERMINATION OF A FORCE FUNCTION FROM GIVEN PARTICULAR INTEGRALS СтатьяINOSTROSA R.OR.Differential Equations. Том 19. 1983. С. 713-720
DIFFERENTIAL PROPERTIES OF FUNCTIONS OF A SPHERE СтатьяZHIDKOV G.V.Differential Equations. Том 19. 1983. С. 1525-1535