Vector-meson contributions to N-N OBEP

We discuss the various forms of one-vector-meson exchange contributions to the N-N interaction which have been used within the Schrödinger-Pauli equation or within a two-particle Dirac equation. These are the Kemmer interaction, the unconstrained four-vector interaction and the Breit-Green interaction. If one postulates that the limit as m goes to zero gives Breit's interaction of electrodynamics, then the 3rd is the appropriate potential. The transition to the co-ordinate space is discussed for potentials calculated in momentum space and a simpler approximation in co-ordinate space is given. Generalized or regularized Yukawa functions are found to improve the convergence of the approximations.