Long-Term Experiences with an Iterative Design of a QR-Code-Based Payment System for Beverages. - Max-Emanuel Maurer; Alexander De Luca; Alina Hang; Doris Hausen; Fabian Hennecke; Sebastian Loehmann; Henri Palleis; Hendrik Richter 002; Simon Stusak; Aurélien Tabard; Sarah Tausch; Emanuel von Zezschwitz; et al. (INTERACT (4), 2013)