The citation index has come a long way. The process of searching for articles that have cited a previously published work used to be a manual and time consuming endeavor. Now that most indices are online, cited reference searching has become much quicker and more graphically powerful. The following databases have cited reference search features.
The Institute of Electrical & Electronics Engineers (IEEE) Xplore Digital Library provides full-text access to journals, transactions, and magazines and conference proceedings published since 1998 and IEEE standards from 1948 to the present.