Is the Encyclopedia for Life Support Systems (EOLSS) a legitimate source?
It appears to be a completely earnest and legitimate effort, and I at least recognize a few names that appear to be involved. It also appears to be pretty old in Internet Time, dating from around 2002.  This makes me think that it's basically an idealistic but largely abandoned project, which would certainly account for its design.  It's also huge and almost certainly poorly curated, which means that there's no reason to think its quality will be uniform.

As such, I would recommend against using leaning on it strongly for any assertion, just because it's hard to tell what you've really got ahold of when you're reading it.  If you find something in it useful, look for the other review papers that the authors will likely have written or have cited, and work from there instead; cite it if you found it useful, but make sure that anything important has another source as well.