1. Fourier Analysis and Nonlinear Partial Differential Equations;Bahouri,2011
2. Notes on some points in the integral calculus LI: on Hilbert's double-series theorem, and some connected theorems concerning the convergence of infinite series and integrals;Hardy;Messenger Math.,1919
3. Note on a theorem of Hilbert;Hardy;Math. Z.,1920
4. Perturbation Theory for Linear Operators;Kato,1966
5. Spectral theory of the operator (p2+m2)1/2−Ze2/r;Herbst;Commun. Math. Phys.,1977