I used to consult many dictionaries and encyclopaedia to improve my background. For this purpose I used to visit the libraries. But one does not have to waste time and money. I wanted to improve my background to become an author of (text)book. That was way before the year 2000.
Nowadays so much stuff one gets online that the need for personal attendance in the library is reduced, if not completely obviated. Here I am listing a few sites that I use. So can you.
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SITE (All of them are NOT free sites):
1. Oxford English Dictionary (www.oed.com)
2. Canbridge Dictionary
3. Encyclopedia Americana
4. Encyclopaedia Britannica
5. Collins Dictionary (www.collinsdictionary.com)
6. Webster's Dictionary
7. American Heritage (https//:ahdictionary.com)
8. www.dictionary.com
9. www.wikipedia.org
(may be expanded)
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You can approach a libray to improve access. They may have web-enabled access also. But remember some libraries may have story books/newspapers only that are good for improving speaking and writing ability in colloquial slang. Policies of the old Congress Govt (pre-Jyoti) and the Left governments in West Bengal had been different. You have to make the best use of the resources available.
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Editor notes: I am experiencing difficulty hyperlinks online. The same would be completed as soon as the problems are fixed.