Add two CCS'20 papers and one DICG'20 paper.

It's been a good year for anti-censorship research.

header.tpl

@@ -180,7 +180,7 @@
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         <img class="top-icon" src="img/update-icon.svg" alt="update icon"/>
         <a
-        href="https://github.com/NullHypothesis/censorbib/commits/master">Last update: 2020-11-10</a>
+        href="https://github.com/NullHypothesis/censorbib/commits/master">Last update: 2020-11-19</a>
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references.bib

@@ -1,3 +1,30 @@
+@inproceedings{Barradas2020b,
+	author = {Diogo Barradas and Nuno Santos},
+	title = {Towards a Scalable Censorship-Resistant Overlay Network based on {WebRTC} Covert Channels},
+	booktitle = {Distributed Infrastructure for Common Good},
+	publisher = {ACM},
+	year = {2020},
+	url = {https://www.gsd.inesc-id.pt/~nsantos/papers/barradas_dicg20.pdf},
+}
+
+@inproceedings{Barradas2020a,
+	author = {Diogo Barradas and Nuno Santos and Lu\'{i}s Rodrigues and V\'{i}tor Nunes},
+	title = {Poking a Hole in the Wall: Efficient Censorship-Resistant {Internet} Communications by Parasitizing on {WebRTC}},
+	booktitle = {Computer and Communications Security},
+	publisher = {ACM},
+	year = {2020},
+	url = {https://www.gsd.inesc-id.pt/~nsantos/papers/barradas_ccs20.pdf},
+}
+
+@inproceedings{Raman2020c,
+	author = {Ram Sundara Raman and Prerana Shenoy and Katharina Kohls and Roya Ensafi},
+	title = {{Censored} {Planet}: An {Internet}-wide, Longitudinal Censorship Observatory},
+	booktitle = {Computer and Communications Security},
+	publisher = {ACM},
+	year = {2020},
+	url = {https://www.ramakrishnansr.com/assets/censoredplanet.pdf},
+}
+
 @inproceedings{Alice2020a,
 	author = {Alice and Bob and Carol and Jan Beznazwy and Amir Houmansadr},
 	title = {How {China} Detects and Blocks {Shadowsocks}},