Heads Up poker e-books, any recommendation ?

[PlayHunter]

I am looking to learn heads up poker, mainly for cash games, but for tournaments as well. Limit and No Limit as well.

I have some articles, but I am interested to know if there is any book (preferable ebook) which can basically fully detail for every aspect and type of opponent ?

 

[gnarus]

Not an ebook but husng has some free videos I found helpful.