Lara Dourado, Paulo Silva, Clóvis Peres, and Daniel Díaz. “Challenges and Opportunities for a Fiscal Blockchain”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 87, no. 1, Apr. 2022, pp. 117-3, https://www.asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/7520.