1. Blockhash Contract. https://github.com/amiller/ethereum-blockhashes
2. Etherpot. https://etherpot.github.io/
3. The rise and rise of bitcoin. Documentary. http://bitcoindoc.com/
4. Smart Contract Programming Open Course Materials. http://mc2-umd.github.io/ethereumlab/
5. Ahamad, S., Nair, M., Varghese, B.: A survey on crypto currencies. In: International Conference on Advances in Civil Engineering (2013)