1. L. C. Evans: Partial Differential Equations. Americal Mathematical Society, Providence, R.I., 1998.
2. G. Köthe: Topologische Lineare Räume I. 2nd edition. Springer, Berlin, 1966.
3. R. Meise and D. Vogt: Introduction to Functional Analysis. Clarendon Press, Oxford, 1997.
4. M. Reed and B. Simon: Methods of Modern Mathematical Physics, vol. I: Functional Analysis. Revised and enlarged edition. Academic Press, San Diego, 1980.
5. W. Rudin: Real and Complex Analysis. 3rd edition. McGraw-Hill, New York, 1987.