diff --git a/paper.bib b/paper.bib
index d38be9f..e55e4ed 100644
--- a/paper.bib
+++ b/paper.bib
@@ -139,7 +139,7 @@ @article{Reul2022
   title    = "Modeling Behavioral Change in Transport Futures",
   journal  = "SSRN preprint",
   year     = 2022,
-  doi = "http://dx.doi.org/10.2139/ssrn.4230060"
+  doi = "10.2139/ssrn.4230060"
 }
 
 @article{Reul2023,