Miguel Virasoro and Joel Shapiro found a different amplitude now understood to be that of closed strings, while Ziro Koba and Holger Nielsen generalized Veneziano's integral representation to multiparticle scattering.
Miguel Virasoro a Joel Shapiro našli inú amplitúdu, dnes chápanú ako uzatvorené struny, kým Ziro Koba a Holger Nielsen zovšeobecnili Venezianove integrálne zastúpenie multičasticového rozdelenia.