H. Dinter, M.K. Czwalinna, C. Gerth, K.P. Przygoda, R. Rybaniec, H. Schlarb, and C. Sydlo,
   "Prototype of the Improved Electro-Optical Unit for the Bunch Arrival Time Monitors at FLASH and the European XFEL",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper TUP049, pp. 478-482,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-TUP049,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/tup049.pdf, 2015.