  The parameters of ten supersoft X-ray sources (RX J0439.8-6809, RX
J0513.9-6951, RX J0527.8-6954, CAL 87, CAL 83, 1E 0035.4-7230, RX J0048.4-7332,
1E 0056.8-7154, RX J0019.8 +2156, RX J0925.7-4758) observed by ROSAT obtained
using blanketing LTE model atmospheres are analyzed. The consistency of the
resulting parameters with a model with stable/recurrent burning on the surface
of the white dwarf is studied. The luminosity and sizes of seven of the sources
are in good agreement with this model. The masses of the white dwarfs in these
sources are estimated. A formula that can be used to estimate the masses of
white dwarfs in classical supersoft sources based on their effective
temperatures is presented.
