%\cite{Plath:FEL2015-WEP029} \bibitem{Plath:FEL2015-WEP029} T.~Plath, S.~Ackermann, J.~Bödewadt, and C.~Lechner, \textquotedblleft{Influence of Seed Laser Wavefront Imperfections on HGHG Seeding Performance}\textquotedblright, % in \emph{Proc. FEL2015}, WEP029, pp. 643--645, % in \emph{Proc. FEL2015}, Daejeon, Republic of Korea, August 2015, paper WEP029, pp. 643--645, in \emph{Proc. 37th International Free Electron Laser Conference (FEL2015)}, Daejeon, Republic of Korea, August 2015, paper WEP029, pp. 643--645, ISBN: 978-3-95450-134-2, \url{http://accelconf.web.cern.ch/AccelConf/FEL2015/papers/wep029.pdf}, doi:10.18429/JACoW-FEL2015-WEP029, 2015.