  The elastic electron-proton scattering data are analysed in order to
determine proton charge and magnetic rms radii, r_E and r_M. Along with the
usual statistical error, we try to estimate a systematic error in the radii,
caused by the inadequacy of particular form factor parameterization employed.
The range of data to use in the analysis is chosen so as to minimize the total
(statistical + systematic) error. We obtain r_E = 0.912 +- 0.009 (stat) +-
0.007 (syst) fm, and r_M = 0.876 +- 0.010 (stat) +- 0.016 (syst) fm. The
cross-section data were corrected for two-photon exchange. We found that
without such corrections obtained r_E and r_M are somewhat smaller while the
quality of fit is worse.
