Reference

http://en.wikipedia.org/wiki/Reference

Site
http://www.reference.com/

Word
http://www.wordreference.com/

Desk
http://www.refdesk.com/

Tube
https://www.youtube.com/results?search_query=Reference

Slides
http://www.slideshare.net/search/slideshow?searchfrom=header&q=Reference

Me
https://www.refme.com

Work
https://www.refworks.com

Seek
https://www.refseek.com/