Good sites, books and exercises to improve technique

Hi, so I've been drumming for a few years now and would like to think I'm alright however I feel at times my technique is not quite as good as it should be (particularly with my feet). I recently bought a pearl eliminator double bass pedal and am fairly new to double pedals and am wondering if anyone could recommend any good sites or books on how to improve. I have books such as stick control which I am thinking of trying using my feet. For most of my time playing drums I have used been playing heel down but from what I have been reading online, heel up seems to be preferred and am interested in seeing what the fuss is about but am struggling a little when using it.

Was wondering if anyone could recommend good ways for me to develop my playing ability as I feel sometimes at faster speeds my playing can get a little sloppy.

Cheers

Good sites, books and exercises to improve technique