Avoid books by John Patrick. I read his latter book on blackjack and his advice was not math based, just based upon his opinions on everything. Also his tone in the book was so arrogant it made me want to vomit. The only things he did talk about that have any relevance were about bankroll managment. But then again, his main advice was to "win 20% of your trip bankroll and get out of the casino ASAP" I'm sorry, but that's an okay win goal, but if the count is positive I want to benefit from it as best as possible.
He suggested shit like splitting 55 against dealer 6 EVERYTIME. Not to split 10's no matter what the count was. Don't split 88 vs dealer 9 10 or A. Just because "you don't want more money on the table when the dealer is strong."
It's almost like a ploppy wrote a book.. wait.. it IS like a ploppy wrote a book.
Books I would recommend are Blackjack Bluebook by Renzey or any book by Stanford Wong.