Princeton Bitcoin textbook is now freely available
freedom-to-tinker.com
freedom-to-tinker.com
http://www.michaelnielsen.org/ddi/how-the-bitcoin-protocol-a...
(he has other articles I would recommend taking a look at, too --- check them out if you're interested! )
You can build the ePub from source:
https://github.com/bitcoinbook/bitcoinbook
Or get it from oreilly:
Is this really freely available? I'd much rather see Princeton release this book to the public domain.
So it's not really all that free in my opinion, even with your additions. /s