Alison Page & David Waters 
Complete Computer Science for Cambridge IGCSE(R) & O Level Revision Guide [PDF ebook] 

With a practical approach and a strong emphasis on problem solving and computational thinking skills, this revision guide includes all the essential tools to build exam confidence. Closely matched to the Student Book, it is packed with key ideas and practice questions. Written by highly experienced authors and examiners, Complete Computer Science helps to deliver the strongest exam results.