Practical Guide to Software Quality Management (Artech House Computing Library)
5.9 The next step
No text can cover the entire scope of software metrics, but these two are good starting points:
Robert B. Grady. Successful Software Process Improvement, Upper Saddle River, NJ: Prentice Hall, 1997.
John McGarry et al. Practical Software Measurement for Objective Decision Makers, Boston, MA: Addison-Wesley, 2001.