Search for periodic components in the light variations of QSS 3C351

The results of the investigation of periodicity of the light curve of QSS 3C 351 are presented. The results of photographic observations carried out at the Astronomical observatory of the Leningrad University and literature data are used. A combined light curve of QSS 3C 351 containing 180 photometric estimations which cover the time interval from 1966 to 1976 is built. Two methods are used for the solution of the problem of finding the periods: the Yurkevich method which is one of the test period and the Deeming method or Fourier analysis in case of nonuniformly distributed data. An attempt to single out periodicity from 20 to 1000 days for QSS 3C 351 has failed. The result does not contradict the model of a unified body