List of citations in Numdam for : Sobolev spaces of variable order and problems of convexity for partial differential operators with constant coefficients
Colloque International C.N.R.S. sur les équations aux dérivées partielles linéaires, Astérisque, no. 2-3 (1973), pp. 325-341.
Annali della Scuola Normale Superiore di Pisa - Scienze Fisiche e Matematiche, Serie 3, Volume 27 (1973) no. 3, pp. 471-490.