R. Ianconescu, A. Gover, E. Hemsing, A. Marinelli, and A. Nause,
   "Sub-Radiance and Enhanced-Radiance of Undulator Radiation from a Correlated Electron Beam",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper MOP078, pp. 221-226,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-MOP078,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/mop078.pdf, 2015.