I have borrowed a number of books from the University library. I had a look inside each one and here I produce a list of titles you might want to read, if you're interested in software metrics (OO product metrics mainly).

• Kan, Stephen. Metrics and Models in Software Quality Engineering. Boston: Addison-Wesley, 1995.
  ISBN 0-201-63339-6
  pp.253-272 (Chapter 10)

• Henderson-Sellers, Brian. Object-oriented metrics: Measures of Complexity. New Jersey: Prentice Hall PTR, 1996.
  ISBN 0-13-239872-9
  pp. 109-164 (Chapter 6)

• Pressman, Roger. Software Engineering: A practitioner's approach, 6th edition. New York: McGraw-Hill, 2005.
  ISBN 007-123840-9
  pp. 461-497 (Chapter 15)

• Sommerville, Ian. Software Engineering, 4th edition. Addison-Wesley Publishing Company, 1992.
  ISBN 0-201-56529-3
  pp. 598-603 (Chapter 31, Section 4)

I also found an annotated bibliography of some 541 works in the area of Object-Oriented Metrics.
It's well worth checking out!