Sven Woop.
  <b>RPU: A Programmable Ray Processing Unit for Realtime Ray
  Tracing</b>.
  In <i>Proceedings of ACM SIGGRAPH 2005 Papers</i>, 2005.
  <A HREF="http://vis.cs.brown.edu/results/bibtex/Woop-2005-RPR.bib">(bibtex:
  Woop-2005-RPR)</A>.<br />