Ask HN: App/Workflow for creating a reference book?

I have a few subjects that I study regularly and extensively and try to keep a "study journal" in hopes that one day with minimal effort I can turn it into an encyclopedia/dictionary of sorts. Premature optimisation keeps me from locking into one until I really find what I'm looking for. Gitbook seems interesting, so do some wikis (zim, vim wiki, org mode) A built-in (bolt-on) concordance generator would be awesome. Has anyone done anything similar?