Best book/articles on heads up play

[Phill S]

Ive been playing full table sit and goes largely for the past couple of years with varied sucess, and recently ive been thinking of expanding beyond this, with heads up play exciting me somewhat; Negreanu's challenges had a little influence, but ive also played and enjoyed playing heads up sit and goes over on stars.

Ive done a little research, but wont pretend its been comprehensive, and ive found a lot of conflicting advice.

Basicly im looking for a few pointers to get me started. Anything and everything that you considered useful to you.

As far as im aware, there are no heads up poker books, but perhaps there are a few less specialised ones that have good heads up sections?

Thank you for any help you may give me,

Phill