K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, and M. Vogt,
   "Status of the Soft X-Ray FEL User Facility FLASH",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper MOP014, pp. 61-65,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-MOP014,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/mop014.pdf, 2015.