Below is a selection of betting books that allaboutbetting has read and used in the past. The contain loads of useful information including three of the Racing Post's expert series on, their guide to betting exchanges, betting on horses and betting on sports. These are packed with useful information and are make excellent reference guides.
There is also Nick Mordin's guide to horse race betting systems which you will refer to again and again and his book Betting For A Living which tells of his experiences when he tried the life of a professional gambler for a year.
Also recommended is the biography of Dave Nevison, a guy who as been a professional gambler for a number of years. This is full of excellent stories.
All these are sold through the trusted website Amazon.