  We would like to discuss, within the inherent historical context, upon one of
the main works of fundamental physics which has led to the formulation of the
early resonance dual models prior to string theory. In fact, we shall focus on
certain aspects of the fundamental Tullio Regge work of 1959, to be precise, on
certain mathematical methods handled by him to pursue his original intentions
mainly motivated to prove some double dispersion relations into the framework
of non-relativistic potential scattering.
