H.T. Li, Q.K. Jia, L. Wang, and S.C. Zhang,
   "DESIGN OF THE MID-INFRARED FEL OSCILLATOR IN CHINA",
   in Proc. 37th International Free Electron Laser Conference, Daejeon, Republic of Korea, August 2015, paper TUP028, pp. 427-429,
    ISBN: 978-3-95450-134-2,
    doi:10.18429/JACoW-FEL2015-TUP028,
    http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/tup028.pdf, 2015.