1. Berezhiani, V.I., Mahajan, S.M.: Phys. Rev. Lett. 73, 1110 (1994)
2. Berezin, Y.A., Karpman, V.I.: Sov. Phys. JETP 46, 1880 (1964)
3. Burns, M.L.: In: Burns, M.L., Harding, A.K., Ramaty, R. (eds.) Positron-Electron Pairs in Astrophysics. American Institute of Physics, Melville (1983)
4. De Vito, M., Pantano, P.: Lett. Nuovo Cimento 40, 58 (1984)
5. Fiandrini, E., Esposito, G., Bertucci, B., et al.: Space Weather 2, S09S02 (2004)