Schweigert, V.-A., & Geyer-Schulz, A. (2019). The Impact of the General Data Protection Regulation on the Design and Measurement of Marketing Activities: Introducing Permission Marketing and Tracking for Improved Marketing & CRM Compliance with Legal Requirements. Journal of Marketing Development and Competitiveness, 13(4). https://doi.org/10.33423/jmdc.v13i4.2352