Does a company file documents with the SEC? Is their stock traded in a public stock exchange? Then it is public.
The Library has a number of useful databases and you can also find good information on some reliable web resources.
If you are off-campus, on clicking a link you will be asked to log in using your myStevens username and password.
Don't forget to check the company's website for corporate info. Look for sections labeled "Corporate" or "Stockholders" for financial and governance data.
The following resources will provide company info for this type of organization.
Mergent Online, Hoover's Company Profiles, Reference USA or other company info databases list the company's industry codes (SIC and/or NAICS for American companies). Look for a company by name, and you can then use the industry code to find other companies in the same line of work.