You can use a variety of sources to find information about your theorist.
1. You can use subject encyclopedias or other reference works to locate overview information about their life and work. These are available as individual ebooks and in reference ebook collections.
2. Scholarly and trade journals can provide articles that provide additional detail about the theorist and their work. These can be located by searching in discipline specific article databases.
3. If you want to dig deeper look for books that cover their life, theories, or are authored by the theorist. Check CLICsearch for books or look in ebook databases with relevant content.