Harmonic analysis of the librational model of the lunar liquid core

A method for constructing a theory of rotation of the Moon, which has a liquid core, is presented. The solution to the problem is carried out within the framework of the Poincaré method, which allows one to consider the rotational motion of a body with a cavity filled with a homogeneous incompressible liquid located in the gravitational field. A mathematical apparatus for solving a similar problem for the simplified model of a two-layer Moon is given.