Of interest, the Mathematica Tutorial Collection:
" .... When we released Version 6 in May 2007, Mathematica was reinvented. We also reinvented something else that Mathematica has long been known for: its extensive and detailed product documentation. While some appreciated the recrafting of our tutorial content as stand-alone electronic documents, others missed the narrative of the book, and let us know it. Which is a good thing, because it led to the creation of the Wolfram Mathematica Tutorial Collection ... "