1. See for instance A. Krzywicki, these proceedings, and references therein.
2. A. Ballestrero, R. Page and E. Predazzi; Nuovo Cimento Letters 15, 57 (1 976); see also: M. Anselmino, A. Ballestrero and E. Predazzi: “Evidence for clusters of growing mass” — preprint (1976). In this paper complete references to previous work are given.
3. Brazil-Japan Emulsion chamber Collaboration: Proc, of the 14th Inter. Cosmic Ray Conference, Munich (1975), Vol.7 and references therein.
4. See, for instance: M. Hama, M. Nagasaki and H. Suzuki, Rikkyo Univ. preprint RUP-7 6–15 (1976)
5. M. Anselmino, A. Ballestrero and E. Predazzi: “Convolution rules for cluster models”, University of Bielefeld preprint BI-TP 76/19.