Most sites offering business cases require you to purchase what you want. There are some library resources that can give you access to cases, however. When searching the following databases, try search for a topic and add the phrase "case study."
EXAMPLE: Amazon and "case study"
EXAMPLE: ethics and case study.
All materials in these databases are free for your use.
ABI/Inform complete includes a wide-range of materials full-text articles from journals, trade publications, and news sources such as the Wall Street Journal. The database also contains specialized information such as company profiles, market information and analysis, economic data, working papers, and business dissertations.
Business Source Premier is a good, all-around database that provides access to variety of content, including journals, newspapers, trade publications SWOT analyses, industry reports, and more. You can limit your search by company name or NAICS code. You can also set up alerts to let you know if new information is published on your company or topic.
There are some open access business case sources available online. You can try searching one of these sources: