Comment on "The separation of variables and bifurcations of first   integrals in one problem of D.N.Goryachev" by Pavel E. Ryabov   (Archive:1102.2588v1)
  We prove that in the Ryabov paper an application of the geometric Kharlamov method to the Goryachev system yields noncommutative "new variables of separation" instead of the standard canonical variables of separation. 
A.V. Tsiganov
nlin.SI