Privacy and identity management 15th IFIP WG 9.2, 9.6/11.7, 11.6/SIG 9.2.2 International Summer School, Maribor, Slovenia, September 21–23, 2020, revised selected papers - Friedewald, Michael 1965-; Schiffner, Stefan; Krenn, Stephan 1984- (Springer, 2021)