Current source "without" temp drift

Hi,

I'd like to make a High precision current source with excellent temp drift (10 to the power of -6 or at best better than that). Current: about 0.5 Ampere

At the moment I have an AD624 combined with a Vishay resistor in mind. How can I go further? Is there a place for me to look up stuff like this?

Thanks

Matthias