For an overview on value investing, consider this Investopedia article:

 https://www.investopedia.com/terms/v/valueinvesting.asp

For articles search the following databases:

• ProQuest One Business
• EBSCO-Business Source Ultimate
• EconLit

If you're having trouble accessing a database or getting an error code, try opening the link in a private or incognito window. For further assistance, contact bis@library.illinois.edu.

For Warren Buffett's letters to Berkshire Hathaway shareholders go to Shareholder Letters - 1977-present

Also see Security Analysis by Benjamin Graham. Several copies are available through the Library Catalog.