A singular lagrangian model for N-body relativistic interactions J. Gomis; J. A. Lobo; A. Poch; J. M. Pons — 1984 Annales de l'I.H.P. Physique théorique
A singular lagrangian model for two interacting relativistic particles J. Gomis; J. A. Lobo; J. M. Pons — 1981 Annales de l'I.H.P. Physique théorique