1. Topics in Pseudo-Differential Operators;Seeley,1969
2. Pseudo-differential operators and hypoelliptic equations;Ho¨rmander,1967
3. On local solvability of linear partial differential equations;Nirenberg;Comm. Pure Appl. Math.,1970
4. An algebra of pseudo-differential operators;Kohn;Comm. Pure Appl. Math.,1965
5. A. Caldero´n and R. Vaillancourt, On the boundedness of pseudo-differential operators, to appear.