Many company's will list their mission statement on their web site. Companies will often list their mission in the "About Us" or "Investor's Relations" sections of their web sites.
You can also try Google searches to limit your terms to the company's web site. For example, you could type mission statement site:wholefoodsmarket.com to retrieve Whole Foods Market's mission statement.
Please be aware that some companies might not have a mission statement. You can also try the above Google search with terms such as values or vision. In addition, in the absence of a mission statement you can also search for an interview with the current CEO since they often articulate the company's values in these interviews.
You can also consult Fortune's list of Most Admired Companies.
Search the Pepperdine University Libraries Catalog for books, ebooks, DVDs, journals, and more
Example: I need books on servant leadership.
This is a good database for articles. Some of the articles will discuss your company's values, mission and philosophy. However, search results will not be consistent since more information is available for iconic companies such as Apple or Starbucks than for other corporations.
Example: I am looking for articles about the Cheesecake Factory's, values and culture.
Example: I want to locate interviews with David Overton, the CEO of Chipotle.
Example: I want articles on leadership at the Cheesecake Factory.