What is a good book on executive coaching?

It would not be fair for me to single out any one specific book on executive coaching.
There are many different books, each based on a different theoretical base.
I'd strongly suggest you track down an HBR Research Report "The Realities of Executive Coaching" January2009.
My perspective is that executive coaching is about competency development and is quite different from counselling (which is more psychological) or mentoring (which is more decision-oriented).
However, many executive coaches would have quite different perspectives.

So many books available for executives taring.
But as per my study Executive Coaching: Practices and Perspectives by Jennifer Garvey Berger is best book.
But one more consideration which major part required in executives can be fulfill by Coaching for Leadership: How the World's Greatest Coaches Help Leaders Learn .
Thanks and Regards Kallan Khan (KK)