The resources below are places to start of research on suppliers.
Sometimes news articles, press releases, and trade journals mention a company's suppliers. These databases contain news and trade articles.
The SEC requires companies to report customers that represent more than 10% of their revenues. Search companies' 10-K or 10-Q reports for customers. 8-K reports will report if a key supplier poses a risk to the company's finances.
The Business Library and Collaboration Commons has two Bloomberg Terminals which can map a company to its suppliers and customers. After logging into a Bloomberg Terminal, search for the company's ticker and then enter the function SPLC <Go>. For example, to search for Apple Inc., use: APPL <Equity> SPLC <Go>. The supplier information cannot be printed or saved.
Supplier news can be accessed with function NI SPLC <Go>.