Fig. 1
Evolution of the number of objects in several quasar compiled catalogues: de Veny et al. (1971), the Véron-Cetty & Véron (2010) catalogue, and the Large Quasar Astrometric Catalogue. We also show one of the most ambitious surveys that bring a huge number of quasars to our knowledge: the Sloan Digital Sky Survey (York et al. 2000).
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