Wikipedia is perhaps the most popular reference site online, with millions of high quality articles available on virtually any topic. However, there are limits to what Wikipedia can offer. Here are 47 Wikipedia alternatives you can use to find information, research a paper, get quick answers, and much more.
Wolfram Alpha, a computational search engine, also has a pretty impressive library archive where you can find thousands of downloadable resources from Wolfram research.
The Open Directory Project is a humanly compiled Web directory of a variety of topics, anything from Arts to Health to Sports. Each link has been scrutinized for quality here by at least one pair of eyes, so you know it's going to be good.
8. Open Library
Open Library is an Internet Archive project aimed at compiling one Web page for every book ever published. To date, they have amassed over 20 million records, all of which are freely accessible.
FactBites offers searchers the ability to get comprehensive search results that actually address the context of their search queries, rather than just the keywords. For example, searching for "history of tornadoes" retrieves statistics, state by state information, and scientific background on some of the worst tornadoes documented.