[en] The search for leptons (electrons and muons) 'created' in collisions of strongly interacting particles began about 1964 and was motivated by a growth in the experimental attack on weak interactions at high energies. The Columbia-BNL opening of high energy neutrino physics in 1961, the discovery of a second, muon-type neutrino and the subsequent failure to find the crucial W-particle, all lead to a desperate hope that weak processes could be seen in the collision of hadrons (pions, protons, kaons). Neutrino physics permitted a first quantitative study of weak forces at high energies, a field previously restricted solely to the study of unstable particles. The measurements with neutrinos at Brookhaven and CERN in 1961-63 gave a great boost to the V-A theory with its predictions of neutrino cross sections; a theory which had grown steadily in stature since the observation of parity violation in 1957. A crucial element of this theory is the existence of a mediating particle, the W^+- vector meson, about which much was known from the theory. In fact, the only important property not supplied by 1960 theory was the mass. Neutrino experiments insisted this mass must be greater than 2GeV and this modest limit was due to the relatively low energy of the neutrino beams then available (average energy approximately 1 GeV). This paper reviews the improved experimental systems used since then by Serpukhov, Columbia-Fermilab, Chicago-Princeton, Yale-BNL and other laboratories, and gives the results to date. (Auth.)