Benko Gambit....book recommends?

Jan Pinski's book is good
http://www.amazon.com/Benko-Gambit-Jan-Pinski/dp/9197524387
Neil McDonald's get good reviews as well.
http://www.amazon.com/Benko-Gambit-Revealed-Neil-McDonald/dp/0713488689

gumpty wrote:
.....also does anyone know if this opening has been refuted in GM play yet? or is it still classed as a 'sound' gambit?? many thx in advance for any ideas...
I saw a John Federovitch lecture where he said it was "busted" at GM level because of the b6 benko; a counter gambit by white. I can't remeber the game that was supposed to be the refutation but I think Radjabov was white. This was a couple of years ago mind you they may have come up with new ideas since. I follow SuperGrandmaster events and I havent seen it played once in years. I play the b6 Benko as white myself and have had good results with it. (I disagree that openings don't matter at my sub- expert level as some claim)
The opening goes like this - (i accidently put ...d6 as being the b6 benko but it's actually the move 5.b6 that gives it it's name)
Can anyone recommend to me a book on the Benko?? i want to learn this system and need a book! preferably modern, so as not outdated.....also does anyone know if this opening has been refuted in GM play yet? or is it still classed as a 'sound' gambit?? many thx in advance for any ideas...