These books provide background on understanding and using ratio analysis.
Financial Ratios: How to Use Financial Ratios to Maximize Value and Success for Your Business
Oxford: CIMA, 2008.
Key Management Ratios: The Clearest Guide to the Critical Numbers that Drive Your Business
Englewood Cliffs, NJ: Prentice Hall/Financial Times, 2006.
Handbook of Business and Financial Ratios
Tyran, Michael R.
Englewood Cliffs, NJ: Prentice Hall, 1986.
Quick ratio definitions and terminology look-ups are available in Oxford Reference Online, http://uclibs.org/PID/44006 (the search box in the upper right corner; you even can limit your look-ups to social sciences or business and management definitions only)