-<li><a href="https://github.com/citp/bitcoin-sok">Bitcoin systematization of knowledge</a>
-<li><a href="http://freico.in/docs/freimarkets.pdf">Freimarkets: a bitcoin extension to support user issued assets, p2p lending, options and more.</a>
+<li><a href="https://github.com/citp/bitcoin-sok">Bitcoin systematization of knowledge</a></li>
+<li><a href="http://freico.in/docs/freimarkets.pdf">Freimarkets: a bitcoin extension to support user issued assets, p2p lending, options and more.</a></li>
+<li><a href="http://blockstream.com/sidechains.pdf">Enabling Blockchain Innovations with Pegged Sidechains</a></li>
+<li><a href="https://bitcoin.org/bitcoin.pdf">Bitcoin: A Peer-to-Peer Electronic Cash System</a></li>
+</ul>
+
+<a href="http://sagemath.org/">Sage</a> notebooks:
+<ul>
+<li><a href="secp256k1.ecdsa.sage">ECDSA with secp256k1</a></li>
+</ul>
+
+Implementations of cool things:
+<ul>
+<li><a href="https://github.com/bitcoin/bitcoin">The one that started it all</a></li>
+<li><a href="https://github.com/unsystem/paypub">PayPub: Trustless payments for information publishing on Bitcoin</a></li>
+<li><a href="https://github.com/zw/PoLtree/">proving Bitcoin liabilities, in Clojure.</a> or <a href="https://github.com/olalonde/proof-of-liabilities">Proof of Liabilities, in JavaScript</a></li>
+<li><a href="https://github.com/petertodd/timelock">Create a secret key that can be decrypted in a known amount of time using parallel-serial hash chains.</a></li>
+<li><a href="https://github.com/Blockstream/contracthashtool">Pay to Contract Hash calculator</a></li>