From 1950 till approximately 2000: One-Boson-Exchange (OBE) models dominate. These are models which typically include several low-mass mesons, that is with masses below 1 GeV. Potentials which are based upon the standard non-relativistic operator structure are called "Phenomenological Potentials" Some historically important examples are

• Gammel-Thaler potential ( Phys. Rev. 107, 291, 1339 (1957) and the
• Hamada-Johnston potential, Nucl. Phys. 34, 382 (1962)), both with a hard core.
• Reid potential (Ann. Phys. (N.Y.) 50, 411 (1968)), soft core.
• Argonne \( V_{14} \) potential (Wiringa et al., Phys. Rev. C 29, 1207 (1984)) with 14 operators and the Argonne \( V_{18} \) potential (Wiringa et al., Phys. Rev. C 51, 38 (1995)), uses 18 operators
• A good historical reference: R. Machleidt, Adv. Nucl. Phys. 19, 189 (1989).

Now: models based on chiral perturbation theory. These are effective models with nucleons and pions as degrees of freedom only. The other mesons which appeared in standard one-boson model appear as multi-pion resonances.