%\cite{Geloni:FEL2015-MOP008} \bibitem{Geloni:FEL2015-MOP008} G.~Geloni, V.~Kocharyan, and E.~Saldin, \textquotedblleft{Theoretical Computation of the Polarization Characteristics of an X-Ray Free-Electron Laser with Planar Undulator}\textquotedblright, % in \emph{Proc. FEL2015}, MOP008, pp. 38--42, % in \emph{Proc. FEL2015}, Daejeon, Republic of Korea, August 2015, paper MOP008, pp. 38--42, in \emph{Proc. 37th International Free Electron Laser Conference (FEL2015)}, Daejeon, Republic of Korea, August 2015, paper MOP008, pp. 38--42, ISBN: 978-3-95450-134-2, \url{http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/mop008.pdf}, doi:10.18429/JACoW-FEL2015-MOP008, 2015.