Content: Front Matter....Pages i-iii On Eigenvalues Eigenfunctions and Resolvents of General Elliptic Problems....Pages 1-37 Il Metodo Del Quoziente Di Rayleigh....Pages 41-60 Isoperimetric Inequalities for Eigenvalues and Their Applications ....Pages 107-167 Calcolo degli autovalori e delle autosoluzioni per operatori non autoaggiunti....Pages 169-186 Upper and Lower Bounds for the Torsional Rigidity and the Capacity, Derived from the Inequality of Schwarz....Pages 187-201 Fredholm Eigenvalues and Conformal Mapping....Pages 203-234