1. Linac coherent light source, http://www.ssrl.slac.stanford.edu/lcls
2. Cornell energy recovery linac, http://erl.chess.cornell.edu
3. Mit-bates x-ray laser, http://mitbates.mit.edu/xfel/
4. http://www.sc.doe.gov/production/bes/BESAC/20%20year%20report.pdf