A few days ago in the
#dailyPaperChallenge I read Veneziano's proposal for a 4-point amplitude. This Friday, my
#paperOfTheDay was "Alternative Construction of Crossing-Symmetric Amplitudes with Regge Behaviour" from 1969, were another, more general, expression is proposed by Virasoro. Overall, the spirit is very similar to Veneziaon's article: Propose a formula and discuss its properties. In particular, the Virasoro amplitude reduces to the Veneziano one if an extra condition is imposed, and at the same time it is argued that this condition is not satisfied for some realistic scattering processes, and therefore Virasoro's amplitude should be expected to better reflect reality than Veneziano's. Again, such heuristic arguments have become somewhat obsolete by now since we now know
#QCD as a fundamental theory, and don't have to guess amplitudes any more. Still, the Virasoro amplitude stays relevant for certain theoretical considerations.
https://journals.aps.org/pr/abstract/10.1103/PhysRev.177.2309