Reference: dictionaries, encyclopedias and more!  Tags: dictionaries encyclopedias atlases  

Encyclopaedia Britannica: a more scholarly encyclopedia.

Funk & Wagnells: a good basic encyclopedia.

Grolier: the Encyclopedia Americana, Grolier Multimedia Encyclopedia (middle school and up) &
New Book of Knowledge (elementary school and up) are all available at this site.

Hutchinson Unabridged Encyclopedia with Atlas and Weather: an online version of a one volume encyclopedia.

World Encyclopedia: another straightfoward one volume encyclopedia, online.