1. Calcul symbolique et propagation des singularités pour les équations aux dérivées partielles non linéaires;Bony;Ann. Sci. Ecole Norm. Sup. 4 Ser.,1981
2. The Dirichlet problem for nonlinear second order elliptic equations. II. Complex Monge–Ampére and uniformly elliptic equations;Caffarelli;Comm. Pure Appl. Math.,1985
3. The Dirichlet problem for nonlinear second order elliptic equations. I. Monge–Ampére equations;Caffarelli;Comm. Pure Appl. Math.,1984
4. Sulla differenziabilita' e l'analiticita' delle estremali degli integrali multipli;De Giorgi;Mem. Accad. Sci. Torino Cl. Sci. Fis. Mat. Natur. (3),1957
5. Subelliptic eigenvalue problems;Fefferman,1981