Order-$\alpha_s^3$ determination of the strange quark mass
  We present a QCD sum rule calculation of the strange-quark mass including four-loop QCD corrections to the correlator of scalar currents. We obtain $\bar m_s(1$ GeV$)=205.5\pm 19.1$ MeV. 
K.G. Chetyrkin, D. Pirjol and K. Schilcher