The page you are reading is part of a draft (v2.0) of the "No bullshit guide to math and physics."
The text has since gone through many edits and is now available in print and electronic format. The current edition of the book is v4.0, which is a substantial improvement in terms of content and language (I hired a professional editor) from the draft version.
I'm leaving the old wiki content up for the time being, but I highly engourage you to check out the finished book. You can check out an extended preview here (PDF, 106 pages, 5MB).
[ Widespread piracy of ebooks is coming up ]
http://www.themillions.com/2010/01/confessions-of-a-book-pirate.html
via http://news.ycombinator.com/item?id=4992595
Quote: Textbook, programming and technical manuals are all over the place and its very easy to obtain almost anything you want. I assume there are more sources for that material, and that their high price is a larger factor in people deciding to pirate them.