Bibliographic mining is a specific research technique that can prove highly effective once you've found a few relevant articles. It is sometimes called backward citation searching or cited reference searching.
Once you have found a few relevant articles providing insight into your research question, take some time to scan through the bibliographies of these articles. Bibliographies -- also called References -- can provide you with picture of the thinking and research on your topic up to the time the article was published. It gives you a snapshot of the sources that influenced the author's work, and can help you identify key authors, theories, and publications related to your topic.
Metadata mining is a research strategy that involves examining the structured information about a source—like subject headings, keywords, and classifications—to uncover related topics and resources. This approach helps you discover broader or narrower areas of research connected to your topic.
When you locate a relevant article, book, or database record, look closely at its metadata. This metadata typically includes subject headings, keywords, classification codes, and sometimes abstracts. These terms are carefully assigned by authors or librarians to categorize the content. By reviewing these terms, you can identify other sources categorized under the same subjects, helping you expand or refine your search. This can lead you to new articles, books, or databases that you might have missed with simple keyword searches.