No Limit Hold 'em: Theory and Practice OR Professional No-Limit Hold

[Asheh]

One thing ive never really grasped in poker is the theory behind equity/fold equity/implied odds etc.

I understand how these work, but never really got to grips with applying them to my game. I want to learn more about the maths and theory behind these and more so I can understand the posts people make analyzing a hand + ranges etc.

Which book would be most useful to me?

Cheers
Ash.