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   "Estimate of Free-Electron Laser Gain Length in the Presence of Electron Beam Collective Effects",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper MOC03, pp. 24-28,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-MOC03,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/moc03.pdf, 2015.