1. Ready, steady, go?-Results of the third BIS survey on central bank digital currency. https://www.bis.org/publ/bppdf/bispap114.htm/
2. Report on a digital euro. https://www.ecb.europa.eu/pub/pdf/other/Report_on_a_digital_euro 4d7268b458.en.pdf/
3. Progress on research and development of E-CNY in China
4. Gupta, Y.K., Jeswani, G., Pinto, O.: M-Commerce offline payment. SN Comput. Sci. 3(1), 1–11 (2022)
5. Kutubi, M.A.A.R., Alam, K.M.R., Morimoto, Y.: A simplified scheme for secure offline electronic payment systems. High-Confidence Comput. 1(2), 100031 (2021)