NetAdvantage (especially detailed financial information and investment analyst reports)
D&B Hoovers (includes company 'triggers' - news events with potential impact)
Mergent Online (uniquely includes ownership information and limited supply chain information)
Morningstar (mostly focused on investment information, but also includes financials and key ratios)
There are more. There is an entire library Guide to walk you through further company research resources, but you can also email the Business Librarian for further assistance.
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