J. Zemella, W.M. Fawley, R.R. Lindberg, and T.J. Maxwell,
   "Time Dependent Study for an X-ray FEL Oscillator at LCLS-II",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper TUP030, pp. 433-435,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-TUP030,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/tup030.pdf, 2015.