2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/225698This article contains a summary of the author's contributions, one in collaboration with K. Bardakci, to dual models and string theory prior to the mid-seventies. Other workers' contributions, during and subsequent to this period, are mentioned in order to relate our work to the general development of the subjectContribution to the volume "The Birth of String Theory", eds. A. Cappelli, E.Castellani, F. Colomo, P DiVecchiaHigh Energy Physics - TheoryHistory and Philosophy of Physicstext