1. N. Iucci, M. Parisi, M. Storini, G. Villoresi, 16th Int. Cosmic Ray Confer., Vol. 3, Kyoto, 1979, p. 491
2. T.S. Bastin, R.B. McKibben, J.A. Simpson, 16th Int. Cosmic Ray Confer., Vol. 12, Kyoto, 1979, p. 324
3. G.A. Bazilevskaya, M.S. Grigoyan, A.I. Saldkova, Sov. Phys.-Lebedev Institute Rep. no. 3, 1984
4. G.A. Bazilevskaya, E.S. Vernova, M.T. Tyasto, M.S. Grigoryan, A.I. Sladkova, 20th Int. Cosmic Ray Confer., Vol. 4, Moscow, 1987, p. 31
5. G.A. Bazilevskaya, M.B. Krainev, V.S. Makhmutov, A.I. Sladkova, 24th Int. Cosmic Ray Confer., Vol. 4, Rome, 1995, p. 572