In Business Source Elite:
When searching, use the term "case review" and any topic you would like to focus on. For example, you could search for "case review" AND Starbucks.
You can also search specifically in publications such as Harvard Business Review. Once in the database, in the top blue bar, click on "Publications." Then search for your journal title and click on it once it appears. From there, you can browse by publication year or search within the publication.
Always remember to check the checkbox for "Full-Text" so your results only include articles you can access in full-text.
These websites offer free access to a variety of case studies:
CaseStudy.co.in
Arthur Andersen Case Studies in Business Ethics
Learning Edge from MIT Sloan School of Management
CaseNet Media Inc.
These open access (free!) journals are focused primarily on business case studies.
Journal of Case Research in Business and Economics
Journal of Business Cases and Applications