I just uploaded the next draft (v10) of my book on EHR systems. I included a chapter on business cases, and expanded quite a bit on the document tree structure. You can find a diff file for version 10 there as well, if you want to focus on the changes.
Update May 13, 2014: I stupidly linked to a particular draft in the above post. A much better link is this:
…which always points to the most recent draft. Currently I’m on draft 15 and will upload 16 later today.
Sorry about that piece of bad information.