Orlando, E. High Energy Astrophysics, MPI for Extraterrestrial Physics, Max Planck Society;
Abdo, A. A., Ackermann, M., Ajello, M., Baldini, L., Ballett, J., Barbiellini, G., et al. (2009). Radio-loud narrow-line Seyfert 1 as a new class of gamma-ray active galactic nuclei. The Astrophysical Journal Letters, 707(2), L142-L147. doi:10.1088/0004-637X/707/2/L142.