Supplementary reading: Paper by Wang et al., introducing the methodology for measuring semantic drift in ontologies The suggested paper is one of the few recent items of literature offering a concrete way for measuring the drift in semantics. Wang, S., Schlobach, S., & Klein, M. (2011). Concept drift and how to identify it. Web Semantics: Science, Services and Agents on the World Wide Web, 9(3), 247-265. Estimated time required Approx. 3-4 hours.