Combined model of smart cities and electronic paymentsSoe, Ralf-Martin; Mikheeva, OlgaProceedings of the 7th International Conference for E-Democracy and Open Government CeDEM17 : Danube University Krems, Krems, Austria, 17-19 May 20172017 / p. 194-205 : ill https://doi.org/10.1109/CeDEM.2017.11 A unifying theory of electronic money and payment systemsBuldas, Ahto; Saarepera, Märt; Steiner, Jamie; Draheim, Dirktechrxiv.org2021 https://doi.org/10.36227/techrxiv.14994558.v2