You are buying a downloadable PDF file of the book here for $9.95. If you want a paperback copy of the book follow this link to Amazon. The cost on Amazon for a paperback copy is $17.95. This is the full Gospel Principles Manual from The Church of Jesus Christ of Latter-day Saints with a side-by-side commentary. The purpose of the commentary is to help in lesson preparation and in the study of the basic principles of the gospel of Christ. No outside materials were used in the commentary. The only thing I have done is to try to give perspective and breadth of understanding to the basic doctrines within the manual.  This is particularly good as a self-study guide.