@unpublished{TUW-299714, author = {Retscher, G{\"u}nther}, title = {Covid-19 Contact Tracing Apps - Is Bluetooth a Reliable Technique for Distance Estimation}, year = {2021}, note = {invited; talk: GIS Ostrava 2021 - Advances in Localization and Navigation, Ostrava, Czech Republic; 2021-03-17 -- 2021-03-19} }