ScienceCitationIndex

http://www.isinet.com/products/citation/sci/
http://isi01.isiknowledge.com/portal.cgi/

It provides access to current and retrospective bibliographic information, author abstracts, and cited references found in [[http://www.thomsonisi.com/cgi-bin/jrnlst/jloptions.cgi?PC=K|3,700 of the world's leading scholarly science and technical journals]] covering more than 100 disciplines.

SeeAlso JournalImpactFactor