Financial cryptography and data security FC 2021 International Workshops, CoDecFin, DeFi, VOTING, and WTSC, virtual event, March 5, 2021 : revised selected papers - Bernhard, Matthew; Bracciali, Andrea 1963-; Gudgeon, Lewis; Haines, Thomas J. ca. 20./21. Jh; Klages-Mundt, Ariah; Matsuo, Shin'ichiro; Perez, Daniel; Sala, Massimiliano 1969-; Werner, Sam (Springer, 2021)