diff --git a/README.md b/README.md
index b013e88..27063ea 100644
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+++ b/README.md
@@ -174,6 +174,7 @@ Other contributors include:
 The extended version is available [`here`](http://eprint.iacr.org/2016/413). 
 
 [2]  David Jao and Luca DeFeo, "Towards quantum-resistant cryptosystems from supersingular elliptic curve isogenies". PQCrypto 2011, LNCS 7071, pp. 19-34, 2011. 
+The extended version is available [`here`](https://eprint.iacr.org/2011/506).
 
 [3]  Craig Costello, David Jao, Patrick Longa, Michael Naehrig, Joost Renes, and David Urbanik, "Efficient compression of SIDH public keys". Advances in Cryptology - EUROCRYPT 2017, LNCS 10210, pp. 679-706, 2017. 
 The preprint version is available [`here`](http://eprint.iacr.org/2016/963).