On the case of Goryachev-Chaplygin and new examples of integrable   conservative systems on S^2
  The aim of this paper is to describe a class of conservative systems on $S^2$ possessing an integral cubic in momenta. We prove that this class of systems consists off the case of Goryachev-Chaplygin, the one-parameter family of systems which has been found by the author in the previous paper (dg-ga/9711005) and a new two-parameter family of conservative systems on $S^2$ possessing an integral cubic in momenta. 
E.N.Selivanova