diff --git a/digital_currency/README.md b/digital_currency/README.md
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 # Digital Currency
 
-* :scroll: [Bitcoin](bitcoin.pdf)
* :scroll: [PeerCoin](peercoin.pdf)
* :scroll: [PrimeCoin](primecoin.pdf)
\ No newline at end of file
+## External Papers
+
+* [Ethereum: a secure decentralized generalized transaction ledger](https://ethereum.github.io/yellowpaper/paper.pdf)
+
+## Hosted Papers
+
+* :scroll: [Bitcoin](bitcoin.pdf)
+* :scroll: [PeerCoin](peercoin.pdf)
+* :scroll: [PrimeCoin](primecoin.pdf)