diff --git a/references.bib b/references.bib
index 7ba7138..d35e936 100644
--- a/references.bib
+++ b/references.bib
@@ -1174,3 +1174,14 @@ @inproceedings{topology-pet2010
   year = {2010},
   url = {http://www.cosic.esat.kuleuven.be/publications/article-1230.pdf}
 }
+
+@inproceedings{le2015herd,
+  title={Herd: A scalable, traffic analysis resistant anonymity network for VoIP systems},
+  author={Le Blond, Stevens and Choffnes, David and Caldwell, William and Druschel, Peter and Merritt, Nicholas},
+  booktitle={ACM SIGCOMM Computer Communication Review},
+  volume={45},
+  number={4},
+  year={2015},
+  organization={ACM},
+  url={https://conferences.sigcomm.org/sigcomm/2015/pdf/papers/p639.pdf}
+}