1. V. Sarabhai, et al, Proceedings of International Cosmic Ray Conference, Moscow, 1960, V. 4, p. 237.
2. Cosmic-Ray Intensities at Great Depths
3. Cosmic-Ray Particles at Great Depth
4. Cosmic-ray intensity measurements deep undergound at depths of (800÷8400) m w.e.
5. Cosmic ray muons and neutrino;Bugayev,1970