Good books on Special Forces?

Hi,

The title says most of it. A collegue of mine is interested in SF ops
(not just US Special Forces, but any similar organisation), and is
looking for books covering them in general (ie, not books like "Bravo
Two Zero" which only cover one operation).

Any advice?

Later,

Oerjan Ohlson
oerjan.ohlson@telia.com

"Life is like a sewer.
  What you get out of it, depends on what you put into it."
- Hen3ry