Comment on "Calculation of the Quarkonium Spectrum and m(b), m(c) to   Order alpha(s)**4"
  A recent determination of the mass of the b quark, based exclusively on quantum chromodynamics (by avoiding strictly to introduce any phenomenological interaction potential of nonperturbative origin), may be improved by allowing for a merely numerical solution of the corresponding eigenvalue problem. 
Wolfgang Lucha and F.F. Schoberl