Chaos in free electron laser oscillators C. Bruni, R. Bachelard, D. Garzella, G. L. Orlandi and M. E. Couprie Eur. Phys. J. D, 55 3 (2009) 669-677 Published online: 12 September 2009 DOI: 10.1140/epjd/e2009-00245-y