1. Lectures on Elliptic Boundary Value Problems;Agmon,1965
2. Estimates near the boundary for solutions of elliptic partial differential equations satisfying general boundary conditions, II;Agmon;Comm. Pure Appl. Math.,1964
3. Spectral asymmetry and Riemannian geometry, I;Atiyah,1975
4. Propriétés asymptotiques de l'équation de la chaleur sur une variété compacte;Colin de Verdière,1975
5. The Neumann's Problem for Differential Forms on Riemannian Manifolds;Conner,1956