[16]https://docs.keep.network/tbtc/index.pdf

[17]https://www.r3.com/wp-content/uploads/2017/06/chain_interoperability_r3.pdf

[18]https://www.weforum.org/whitepapers/inclusive-deployment-of-blockchain-for-supply-chains-part-6-a-framework-for-blockchain-interoperability

[19]https://polkadot.network/

[20]https://cosmos.network/

[21]https://talk.nervos.org/t/2-0-nervos-unidapp-dapp/5332

[22]https://pay.lay2.dev/#/