Strong, A. W. High Energy Astrophysics, MPI for Extraterrestrial Physics, Max Planck Society;
Allafort, A., Baldini, L., Ballet, J., Barbiellini, G., Baring, M. G., Bastieri, D., et al. (2013). PSR J2021+4026 in the gamma Cygni region: the first variable γ-ray pulsar seen by the Fermi LAT. The Astrophysical Journal Letters, 777(1): L2, pp. 1-8. doi:10.1088/2041-8205/777/1/L2.