P.J.M. van der Slot, H. Freund, and P.J.M. van der Slot,
   "Three-dimensional, Time-dependent Simulation of Free-Electron Lasers",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper TUP004, pp. 331-333,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-TUP004,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/tup004.pdf, 2015.