Op-amps? Need to learn

Does anybody have any good resources on op amps? I can't find any good resource

What do you want to learn?

If you want to see a bunch of sample applications/circuits, the "famous" [u]AN 31[/u] is a great place to start.

If you want to make filters, there's the famous [u]Active Filter Cookbook[/u], but that's an old pre-Intenet book and I assume that you can now find the formulas (to calculate the resistor & capactor values) online.

If you just want to learn the basics of "how they work", I don't know of a handy reference... I'm sure I've got a textbook on my bookshelf, but that should be available online too...

I was more so looking at gain and the mathematics behind op-amps.

I have been using this as a study reference for opamps: http://www.electronics-tutorials.ws/opamp/opamp_1.html

As usual I will refer people to "The Art of Electronics" as a great book to learn practical electronics from - this covers opamps pretty well (possibly a little light on the theory, but the intuition is great).

Alright thanks a lot guys! I'll check both of those out.