Key Ideas > Truncation > Phrases > Boolean Logic > Subjects/Descriptors > Review and Refine > Limiting > Citation Indexes
It is usually possible to do "reference chaining" backwards, by looking at the citations in a journal article or case and then search for those earlier articles, books or cases.
Citation indexes (for journal articles) and citators (for case law) allow searchers to "reference chain" forwards in time, ie to identify later articles or cases that have cited the article or case currently being looked at.
Citation indexes for journal articles include:
Citators for case law: