1. Dauber, P.M., Smith, L.H., 1973. Proceedings of 13th International Ray Conference in Denver, vol. 4, p. 2716
2. Fichtel, C.E., 1971, in: Labuhn and Lüst (Eds.), New Techniques in Space Astronomy, IAU-Symp., vol. 41, pp. 14–36
3. Perspectives of Modern Physics;Greisen,1966
4. Measurement of Gamma-Ray Energies with Two Crystals in Coincidence
5. Kappadath, S.C., 1998. PhD Thesis at University of New Hampshire, USA