On the inversion of eigenvalue problems

The aim of this paper is to draw attention to an apparently forgotten paper ( 1) on the inverse scattering problem in quantum mechanics and to add some generalizations and explanations. In the enormous literature ( 2, 3) which in the course of 15 years has grown up around this problem, nobody appears to have taken advantage of the simple principles on which that paper was based. Several inconveniences and some weak points of current theories are pointed out.