M. Scholz, B. Faatz, S. Schreiber, and J. Zemella,
   "First Simultaneous Operation of Two Sase Beamlines in FLASH",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper TUA04, pp. 297-300,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-TUA04,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/tua04.pdf, 2015.