Sabine Rittmann A methodology for modeling usage behavior of multi-functional systems. 2008 Technical University Munich, Germany 1-191 http://mediatum2.ub.tum.de/doc/635723/document.pdf https://nbn-resolving.org/urn:nbn:de:bvb:91-diss-20071211-635723-1-7 https://d-nb.info/990917932 https://d-nb.info/991797949