%\cite{Hacker:FEL2015-WEP030}
\bibitem{Hacker:FEL2015-WEP030}
    K.E.~Hacker, S.~Ackermann, Ph.~Amstutz, R.W.~Aßmann, A.~Azima, J.~Bödewadt, \emph{et al.},
%   K.E. Hacker \emph{et al.},
   \textquotedblleft{First Lasing of an HGHG Seeded FEL at FLASH}\textquotedblright,
%  in \emph{Proc. FEL2015}, WEP030, pp. 646--649,
%  in \emph{Proc. FEL2015}, Daejeon, Republic of Korea, August 2015, paper WEP030, pp. 646--649,
   in \emph{Proc. 37th International Free Electron Laser Conference (FEL2015)}, Daejeon, Republic of Korea, August 2015, paper WEP030, pp. 646--649,
    ISBN: 978-3-95450-134-2,
    \url{http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/wep030.pdf},
    doi:10.18429/JACoW-FEL2015-WEP030, 2015.