After a special investigation into the stability of seismic stations of the Eurasian continent, a system of reference stations for routine determination of earthquake magnitudes has been selected. A method for determining station corrections in a network of continental dimensions has been developed and tested for PV waves observed by eight Eurasian stations, taking into account the dependence of station corrections on source region. It is assumed that such a homogeneous system of reference stations can eliminate the largest discrepancies in the magnitude determinations.