diff --git a/pdf/2012-SWEET_Serving_the_Web_by_Exploiting_Email_Tunnels.pdf b/pdf/2012-SWEET_Serving_the_Web_by_Exploiting_Email_Tunnels.pdf
new file mode 100644
index 00000000..bf7c1279
Binary files /dev/null and b/pdf/2012-SWEET_Serving_the_Web_by_Exploiting_Email_Tunnels.pdf differ
diff --git a/pdf/2013-Towards_a_Censorship_Analyser_for_Tor.pdf b/pdf/2013-Towards_a_Censorship_Analyser_for_Tor.pdf
new file mode 100644
index 00000000..599c2d8e
Binary files /dev/null and b/pdf/2013-Towards_a_Censorship_Analyser_for_Tor.pdf differ
diff --git a/pdf/2014-Enhancing_Censorship_Resistance_in_the_Tor_Anonymity_Network.pdf b/pdf/2014-Enhancing_Censorship_Resistance_in_the_Tor_Anonymity_Network.pdf
new file mode 100644
index 00000000..bccc7cdf
Binary files /dev/null and b/pdf/2014-Enhancing_Censorship_Resistance_in_the_Tor_Anonymity_Network.pdf differ
diff --git a/pdf/2017-Tor's_Usability_for_Censorship_Circumvention.pdf b/pdf/2017-Tor's_Usability_for_Censorship_Circumvention.pdf
new file mode 100644
index 00000000..989bd405
Binary files /dev/null and b/pdf/2017-Tor's_Usability_for_Censorship_Circumvention.pdf differ