For a fast and useful introduction, you can read the second chapter of the book
"Quantum Mechanics, Vol. I", by Claude Cohen-Tannoudji et al.
You will find here almost all you need to study quantum physics.
For a deeper treatment, you can try,
"Functional Analysis. Volume I.", by Reed & Simon. This is the first volume of the collection Methods of Modern Mathematical Physics.
This post imported from StackExchange Physics at 2014-05-04 14:07 (UCT), posted by SE-user asanlua