1. V. A. Tsarev, J. Rad. Phys. Chem. 75, 805 (2006).
2. G. A. Gusev, B. N. Lomonosov, K. M. Pichkhadze, et al., Kosm. Issled. 44, 22 (2006) [Cosmic Res. 44, 19 (2006)].
3. V. A. Chechin, E. L. Feinberg, G. A. Gusev, et al., Proceedings of the International ARENA Workshop, DESY, Zeuthen, Ed. by R. Nahnhauer and S. Boser (DESY, Zeuthen, 2005), p. 232.
4. N. G. Lehtinen, P.W. Gorham, A. R. Jacobson, et al., Phys. Rev. D 69, 013008 (2004).
5. Y. Takahashi et al., New J. Phys. 11, 065009 (2009).