Martin Rees (1942-) and Dennis Sciama (1926-1999) analyze quasar source count data and discover that the quasar density increases with redshift
Editors. "Quasar density shown to increase with redshift". The Literary Encyclopedia. First published 01 May 2009; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=6666, accessed 27 April 2015.]