• Li, W.: Applying Software Maintenance Metrics in the Object Oriented Software Development Life Cycle, Ph. D., Computer Science Dept., Virginia Tech, Sept. 1992.
• Li, W.; Henry, S.: Maintenance Metrics for the Object Oriented Paradigm, Proceedings of the First International Software Metrics Symposium, May 21-22, Baltimore, pp. 52-60.

"The objects are coupled "

"through certain communication mechanism provided by the object oriented paradigm. The forms of object coupling are coupling through inheritance, coupling through message passing, and coupling through data abstraction."

"The use of inheritance which is not well designed may introduce extra complexity."

"The number of variables having an ADT type may indicate the number of the data structures dependent upon the definitions of other classes. The more ADTs a class has, the more complex the coupling is of that class with other classes."

"Since the local methods in a class constitute the interface increment of the class, NOM (number of methods, d.R.) serves the best as an interface metric."