For journal articles, search the databases ABI/Inform, Business Source Complete, Factiva, and Nexis Uni . 

Business Ethics Quarterly from Cambridge University Press is another good resource for in-depth information about business ethics.  

For Wharton School of Business resources, visit the Legal Studies & Business Ethics program and the Carol and Lawrence Zicklin Center for Business Ethics Research. 

Knowledge at Wharton features articles and podcast episodes on business ethics from Wharton scholars. 

Other resources: 
Penn Libraries Philosophy Research Guide 
Stanford Encyclopedia of Philosophy 

See also:

Where can I find information on normative business ethics?
Where can I find information on corporate governance?
Where can I find environmental, social and corporate governance (ESG) data?