Best sources of reference for aviation paintings?

[ontheborderland]

I'm an illustrator by trade and I'm looking to produce a series of aviation paintings over the next year.

The best examples I've seen all seem to be illustrations of a specific event or encounter that really happened, and are thoroughly researched.

So my question is this: what's the best way to find out about specific details such as exact aircraft model and markings, weapons loudout etc. If I find a scenario that interests me in a book for example, where would be the next best place to go to fill in all of the visual details?

To narrow the field a little, let's confine it to the Battle of Britain for the moment.

Any pointers or advice would be greatly appreciated. Cheers!