diff --git a/references.bib b/references.bib
index 1b6ea08..26feff0 100644
--- a/references.bib
+++ b/references.bib
@@ -105,7 +105,7 @@
 @inproceedings{holl2021pg,
 	  title={Physical Gradients},
 	  author={Holl, Philipp and Koltun, Vladlen and Thuerey, Nils},
-	  booktitle={arXiv},
+	  booktitle={arXiv:2109.15048},
 	  year={2021},
 	  url={https://ge.in.tum.de/publications/},
 }