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Technology In Brief: Coins with fast transaction
Ripple (XRP):
https://coinmarketcap.com/currencies/ripple/
https://ripple.com/files/ripple_consensus_whitepaper.pdf
https://ripple.com/files/xrp_overview.pdf
https://ripple.com/files/ripple_solutions_guide.pdf
IOTA:
https://coinmarketcap.com/currencies/iota/
https://iota.org/IOTA_Whitepaper.pdf
Raiblocks (XRB):
https://coinmarketcap.com/currencies/raiblocks/
https://raiblocks.net/media/RaiBlocks_Whitepaper__English.pdf