If you have already found relevant materials, the citations in those sources are a great way to expand your bibliography. Journal abbreviations are often used in citations and can be misleading. A complete alphabetical list of journal abbreviations and their corresponding titles can be found at: Journal abbreviations.

The primary source for citation searching in the sciences is ISI's Science Citation Index Expanded. You can search for articles themselves, citations of an article, or citations of a specific author. Though not an absolute certainty, the number of citations of a given article can help indicate how influential it has been. The articles that cite the original article could also be useful sources.