↑ Hasan, Omar (2020). "Privacy Preserving Reputation Systems based on Blockchain and other Cryptographic Building Blocks: A Survey" (PDF). ↑ parity: Fast, light, robust Ethereum implementation, Parity Technologies, 2017-12-12, retrieved 2017-12-12 ↑ Gavin, Wood (November 2015). "PoA Private Chains".