If you aren't sure if a company is public or private, try a search in the US Security and Exchange Commission's tool called Edgar. Enter the company name. If you find reports in Edgar, the company is public.
Search all company information at once or search Hoover's or Snapshots individually.
Search both at once:
Search one at a time:
Here are some tips for searching Hoover's or Snapshots for information about companies or industries: