1. and (1990) Proceedings of the CIPS 1990 Conference, Canadian Information Processing Society, Ottawa, Canada, May, 1990.
2. and (1991) ‘Analysis of the maintenance work categories through measurements’, Proceedings of the IEEE Conference on Software Maintenance, Sorrento, Italy, 14–17 October 1991, IEEE Computer Society Press, Washington, DC.
3. (1988) Software Evolution. The Software Maintenance Challenge, John Wiley, Chichester.
4. (1987) see Zvegintzov, N (1991).
5. (1990) 1990 Annual Software Maintenance Survey, Survey conducted and compiled for the Software Maintenance Association, P.O. Box 12004 no. 297, Vallejo, CA 94590, CA, see Zvegintzov, N (1991).