[n] J. Hagel, “Invariants of Betatron Motion and Dynamic Aperture”, in Proc. PAC'87, Washington D.C., USA, Mar. 1987, pp. 1264-1267.
%\cite{Hagel:PAC87} \bibitem{Hagel:PAC87} J. Hagel, \textquotedblleft{Invariants of Betatron Motion and Dynamic Aperture}\textquotedblright, in \emph{Proc. PAC’87}, Washington D.C., USA, Mar. 1987, pp. 1264--1267.
@inproceedings{hagel:pac87, author = {J. Hagel}, title = {{Invariants of Betatron Motion and Dynamic Aperture}}, booktitle = {Proc. PAC'87}, pages = {1264--1267}, paper = {}, venue = {Washington D.C., USA, Mar. 1987}, publisher = {JACoW Publishing, Geneva, Switzerland}, language = {english} }