1. M. G. Aartsen, K. Abraham, M. Ackermann, et al., arXiv:1603.01227v2 (2016).
2. A. Aab, P. Abreu, M. Aglietta, et al., Astrophys. J. 794, 172 (2014).
3. O. Deligny, J. Phys.: Conf. Ser. 531, 012002 (2014).
4. M. Aglietta, V. V. Alekseenko, B. Alessandro, et al., Astrophys. J. 692, L130 (2009).
5. G. B. Khristiansen, G. V. Kulikov, and Yu. A. Fomin, Cosmic Radiation of Ultrahigh Energy (Atomizdat, Moscow, 1975), p. 226 [in Russian].