1. Nakamoto, S.: Bitcoin: A peer-to-peer electronic cash system. Technical report (2008),
https://bitcoin.org/bitcoin.pdf
2. Litecoin,
https://litecoin.org
3. Ripple,
https://ripple.com
4. Mastercoin,
http://www.mastercoin.org
5. BitInfoCharts,
http://bitinfocharts.com/comparison/transactions-marketcap-btc-ltc.html
(accessed on March 28, 2014)