Strong, A. W. High Energy Astrophysics, MPI for Extraterrestrial Physics, Max Planck Society;
Ackermann, M., Ajello, M., Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., et al. (2013). Detection of the characteristic pion-decay signature in supernova remnants. Science, 339(6121), 807-811. doi:10.1126/science.1231160.