Some remarks on conservative symmetric-hyperbolic systems governing relativistic theories Alberto Strumia — 1983 Annales de l'I.H.P. Physique théorique
Main field and convex covariant density for quasi-linear hyperbolic systems : relativistic fluid dynamics Tommaso Ruggeri; Alberto Strumia — 1981 Annales de l'I.H.P. Physique théorique