VizieR online Data Catalogue associated with article published in journal Astronomical Journal (AAS) with title 'Evolution of the X-ray emission of radio-quiet quasars.' (bibcode: 2007ApJ...657..116K)
Kelly, B. C. (Creator), Bechtold, J. (Creator) (2009). X-ray and UV parameters of radio-quiet quasars. Centre de Donnees Strasbourg (CDS). 10.26093/cds/vizier.16570116