1. Bitcoin market capitalization. CoinMarketCap, 2019.
2. International financial statistics. International Monetary Fund, 2019.
3. Can ice cream be money? Perishable medium of exchange;Cuadras-Morató;Journal of Economics,1997
4. Functions and characteristics of money: A lesson to accompany;Federal Reserve Bank of Philadelphia,2013
5. Application of FinCEN's regulations to persons administering, exchanging, or using virtual currencies. FIN-2013-G001;Financial Crimes Enforcement Network,2013