In addition to creating a lot of good self-study books, Cambridge is one of the co-creators of the IELTS. So it’s unsurprising that they also publish the best book for preparing to take the test.
The Official Cambridge Guide to IELTS is written for English learners with a minimum B1 reading level, and offers guidance for how to prepare for both versions of the IELTS (Academic and General Training). In addition, the book includes lots of tips, explanations, exercises, audio and visual examples – plus 8 complete practice tests.
Do note, however, that this book does not teach you vocabulary or grammar. It focuses on listening, reading, speaking, and writing skills – just like the IELTS itself.
[Book] Pdf: PDF