1. Apr. 2018. Beauty Chain | Address 0xc5d105e63711398af9bbjf092d4b6769c82f793d. https://etherscan.io/address/0xc5d105e63711398af9bbff092d4b6769c82f793d
2. Apr. 2018. POSC | Address 0x3d807baa0342b748ec59aa0b01e93f774672f7ac. https://etherscan.io/address/0x3d807baa0342b748ec59aa0b01e93f774672f7ac
3. Apr. 2020. Library UniswapV2Router01. https://github.com/Uniswap/v2-periphery/blob/0335e8f7e1bd1e8d8329fd300aea2ef2f36dd19f/contracts/UniswapV2Router01.sol original-date: 2019-12-09T20:17:43Z.
4. Apr. 2021. Solidity v0.8.0 Breaking Changes --- Solidity 0.8.19 documentation. https://docs.soliditylang.org/en/v0.8.19/080-breaking-changes.html
5. Aug. 2022. Ethereum Development Documentation. https://ethereum.org/en/developers/docs/smart-contracts/testing/#code-audits