Some rigorous results can be derived using a very simple approach to hadronspectroscopy, in which a static potential is associated with non-relativistickinematics. Several regularities of the experimental spectrum are explained bysuch models. It is underlined that certain methods developed for hadronicphysics have found applications in other fields, in particular atomic physics.A few results can be extended to cases involving spin-dependent forces orrelativistic kinematics.
