Schopper, R. High Energy Astrophysics, MPI for Extraterrestrial Physics, Max Planck Society;
Schopper, R., Ruhl, H., Kunzl, T. A., & Lesch, H. (2002). The free electron maser in pular magnetospheres. In W., Becker, H., Lesch, & J., Trümper (Eds.), Proceedings of the 270. WE-Heraeus Seminar on Neutron Stars, Pulsars and Supernova Remnants (pp. 193-199). Garching: Max-Planck-Institut für extraterrestrische Physik.