1. Asymptotic for □u = m2u + G(x, t, u, ux, ut), I;Chadam;Ann. Scuola Norm. Sup. Pisa,1972
2. Asymptotic for □u = m2u + G(x, t, u, ux, ut), II;Chadam;Ann. Scuola Norm. Sup. Pisa,1972
3. On the existence and uniqueness of the equation utt − ∂σi(uxi)∂xi − ΔNut = ƒ;Clements;Canad. Math. Bull.,1975
4. A quasi-linear hyperbolic and related third order equation;Davis;J. Math. Anal. Appl.,1975
5. Sur les problèmes de Cauchy hyperboliques bien posés;Dionne;J. Analyse Math.,1962