Links::Reference

Cambridge Advanced Learners' Dictionary

Free and easy to use. UK and US English.

http://dictionary.cambridge.org/

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Merriam-Webster Dictionary

US English dictionary

http://www.m-w.com/netdict.htm

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Google Scholar

Specifically for academic searches: papers, books, abstracts etc.

http://scholar.google.com/

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Columbia Guide to Online Style

For referencing electronic sources.

http://www.columbia.edu/cu/cup/cgos/basic.html

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Harvard Citation Style Guidelines

For Harvard referencing.

http://www.lib.monash.edu.au/tutorials/citing/harvard.html