Hello
I'm a little bit unsure which version of the A77 you're asking about, but it doesn't matter beacuse I'm going to recommend Gary Friedman who has written a superb book for either..
The first edition of the A77 is covered here: http://www.friedmanarchives.com/alpha77/index.htm
and the second edition here: http://www.friedmanarchives.com/alpha77II/index.htm
His books cover every aspect of the camera, and are written in a very easy to understand format.
He also offers a rick-free guarantee:
"Money-Back Guarantee
Okay, here's the details on the 'risk-free' part. Buy the .pdf format and plow through it for two weeks. If you don't think this book offers the clearest explanations, if you didn't end up learning anything new, or it is not the single best value in terms of dollars-per-knowledge ratio, just send Gary an email and he'll personally refund your purchase price. How can you lose? Gary's books have introduced thousands of people to the joys of photography in a very intuitive way, and his books have been universally praised for being the best out there for the Sony cameras, which makes this an easy offer to make. (This offer does NOT apply to the printed version of the book, for obvious reasons.)"
I've bought a couple of his e-books and can't fault them.
Regards
Andy
