Table of Contents

The origin of the third family, C.S. Wu; heavy leptons, T.D. Lee; lepton physics at CERN and Frascati, N. Cabibbo; search for heavy leptons from time-like photons at CERN, V.F. Weisskopf; the beginning of the physics of leptons, S.C.C. Ting; the basic steps which led to the discovery of the heavy lepton tau - a historical record, C. Villi; concerning the discovery of the heavy lepton, M. Conversi; the roots of the third family, A. Petermann; the search of heavy leptons by A. Zichichi and his collaborators, B.H. Wilk, G. Wolf. Appendices: foundations of sequential heavy lepton searchers, a. Zichichi; answers to claims for priorities on HL and to criticism of the BCF experimental set-up, A. Zichichi.