What can we learn from VIRMOS quasars?
  Large, homogeneous quasar samples are necessary tools for the study of QSO statistics, cosmological tests, large scale structure and AGN evolution. These samples must be complete within well defined flux limits at all redshifts. An observational strategy without previous photometric selection of quasar candidates is described, based essentially on the VIRMOS Survey spectroscopy. 
G. Mathez and E. Hatziminaoglou