M. Xin, K. Safak, P.T. Callahan, F.X. Kaernter, and M.Y. Peng,
   "All-Fiber Approach to Long-Term Stable Timing Distribution System",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper MOP042, pp. 122-125,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-MOP042,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/mop042.pdf, 2015.