Try books written by venerable **Rerukane Chandawimala** thero and venerable **Mankadawala Sudassana** thero.        
As far as I know the if you search, you might find English translations. All books are good. As I know Rerukane Chandawimala theor's books are directly written by referring "thripitaka". Depend on your level select the book. If you are a beginner "Handbook of the Buddhist" will be a great start.