Spectroscopy of Quasar Candidates from SDSS Commissioning Data
  The Sloan Digital Sky Survey has obtained images in five broad-band colors for several hundred square degrees. We present color-color diagrams for stellar objects, and demonstrate that quasars are easily distinguished from stars by their distinctive colors. Follow-up spectroscopy in less than ten nights of telescope time has yielded 22 new quasars, 9 of them at $z> 3.65$, and one with $z = 4.75$, the second highest-redshift quasar yet known. Roughly 80% of the high-redshift quasar candidates selected by color indeed turn out to be high-redshift quasars. 
Xiaohui Fan, Michael A. Strauss, James Annis, James E. Gunn, Gregory   S. Hennessy, Zeljko Ivezic, Gillian R. Knapp, Robert ...