Media type: E-Article Title: Seminar on Differential Equations and Dynamical Systems, II: The period of periodic solutions and charged particles in magnetic fields Contributor: Yorke, James A. Published: Springer Berlin Heidelberg, 1970 Published in: Seminar on Differential Equations and Dynamical Systems, II (1970), Seite 267-268 Language: Not determined DOI: 10.1007/bfb0059946 ISBN: 9783540363064; 9783540049333 ISSN: 0075-8434; 1617-9692 Origination: Footnote: