Here is the best of both worlds.  Encyclopedia.com  provides online content that is free & not password protected AND content that is from reputable sources.  It includes: "verified facts, information, and biographies from trusted sources.  Encyclopedia.com gives you credible answers from published reference works – all in one place: 49 encyclopedias from sources like Oxford University Press and Columbia University Press & 73 dictionaries and thesauruses with definitions, synonyms, pronunciation keys, word origins, and abbreviations."  -- from website.

The only downside to the source is the annoying ads.  But that's the flipside when you don't have to pay for it.

My favorite part of the site is the "Compare side-by-side" feature.  Check out this article on the Iran Hostage Crisis (click on the "Compare side-by-side" tab).  You can see three rather current reference articles all on one page.