A snapshot survey for gravitational lenses among z >= 4.0 quasars. II. Constraints on the 4.0 < z < 5.4 quasar population (vol 131, pg 49 2006)

Gordon T Richards, Zoltan Haiman, Bartosz Pindor, Michael A Strauss, Xiaohui Fan, Daniel Eisenstein, Donald P Schneider, Neta A Bahcall, J Brinkmann, Masataka Fukugita