It's helpful to know your the NAICS & SIC codes for your industry before going into some of the sources below.
For help understanding ratios and how to use them see the following sites:
The financial section of First Research has ratios for most industries.
For ratios of a large companies, it is best to compare with similar corporations.
S&P NetAdvantage Industry Surveys have comparison charts for competing companies.
Mergent allows you to create your own.
For more databases options, see our complete lists by subject or A - Z list.
Business Ratios and Formulas by 
Ratios Made Simple by NAICS codes and the earlier SIC codes are used to define industries.
Use these sources to verify your industry code definitions:
If you search the databases (or any other resource) and find articles that you want that the library does not have access to, you can request them using interlibrary loan. It may take from several days to several weeks for your articles to arrive.
Use this form to request articles. Library staff will contact you when the article arrives and you can pick it up at the circulation desk.