1. Interpolation between subspaces of a Hilbert space, Technical note BN-719. Institute for Fluid Dynamics and Applied Mathematics, University of Maryland, College Park, 1971.
2. Elliptic boundary value problems in domains with point singularities, vol. 52. American Mathematical Society, Mathematical Surveys and Monographs, 1997.
3. Les Methodes Directes en Theorie des Equations Elliptiques. Academia: Prague, 1967.
4. Interpolation of Operators. Academic Press: New York, 1988.
5. Non-homogeneous Boundary Value Problems and Applications, I. Springer: New York, 1972.