1. R. A. Adams,Sobolev Spaces, Academic Press, New York, 1975.
2. H. Amann,Nonlinear elliptic equations with nonlinear boundary conditions, inNew Developments in Differential Equations (W. Eckhaus, ed.), North-Holland Math. Studies 21, 1976, pp. 43–63.
3. Ph. Bénilan,Opérateurs accrétifs et semi-groupes dans les espaces L p (1≦p≦∞), inFunctional Analysis and Numerical Analysis, Japan-France Seminar, Tokyo and Kyoto, 1976 (H. Fujita, ed.), Japan Society for the Promotion of Science, 1978, pp. 15–53.
4. J. Bergh and J. Löfström,Interpolation Spaces. An Introduction, Springer-Verlag, Berlin, 1976.
5. J.-M. Bony,Principe du maximum dans les espaces de Sobolev, C.R. Acad. Sci. Paris, Sér. A,265 (1967), 333–336.