1. A. A. Abdo, M. Ackermann, M. Ajello, W. B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, M. G. Baring, et al., Astrophys. J. 712, 2109 (2010).
2. P. Arumugasami, G. Pavlov, and J. Blake, in Proceedings of the 40th COSPAR Scientific Assembly, August 2–10, 2014, Moscow, Russia (2014).
3. A. V. Bilous, V. I. Kondratiev, M. Kramer, E. F. Keane, J. W. T. Hessels, B. W. Stappers, V. M. Malofeev, C. Sobey, et al., Astron. Astrophys. 5911, 134B (2016).
4. P. A. Caraveo, G. F. Bignami, J. E. Trumper, and E. Joachim, Astron. Astrophys. Rev. 7, 209 (1996).
5. J. P. Halpern, E. V. Gotthelf, N. Mirabal, and F. Camilo, Astrophys. J. 573, L41 (2002).