An Activity-Based Quality Model for Maintainability Florian Deissenboeck, Stefan Wagner, Markus Pizka, Jean-Francois Girad, Stefan Teuchert IN PROCEEDINGS OF THE 23RD INTERNATIONAL CONFERENCE ON SOFTWARE MAINTENANCE (ICSM 2007). IEEE CS PRESS, 2007 https://itestra.com/wp-content/uploads/2018/03/07_itestra_activity_based_quality_model.pdf