Kiumi Akingbehin Bruce R. Maxim A Three-Layer Model for Software Engineering Metrics. 17-20 2006 conf/snpd/2006 SNPD http://doi.ieeecomputersociety.org/10.1109/SNPD-SAWN.2006.12 db/conf/snpd/snpd2006.html#AkingbehinM06