Encyclopaedia Brittanica
Compton's Internactive Encyclopaedia CD ROM
Microsoft Encarta CD ROM
The New American Desk Encyclopaedia
Several small paperback desktop encyclopaedias are on the market, and
while containing nowhere near the depth of information of an
Encyclopaedia Brittanica or the like, they do contain more than
enough information to make you knowledgeable on many subjects.
If your computer has a CD-ROM drive (whose does not, nowadays), a CD
encyclopaedia can provide an extensive amount of information in a
small, affordable format. With the rebates commonly offered
on new software, a good new CD will cost anywhere from $0 to
$40. Even a used or older version of a CD encyclopaedia will do; I
recently purchased a 1997 version of Compton's Interactive Encyclopaedia
for $10 (Canadian).