diff --git a/paper/paper.bib b/paper/paper.bib
index b0e17fd..9974a62 100644
--- a/paper/paper.bib
+++ b/paper/paper.bib
@@ -202,7 +202,7 @@ @article{LIU2020105292
 pages = {105292},
 year = {2020},
 issn = {0950-7051},
-doi = {https://doi.org/10.1016/j.knosys.2019.105292},
+doi = {10.1016/j.knosys.2019.105292},
 url = {https://www.sciencedirect.com/science/article/pii/S0950705119305830},
 author = {Bin Liu and Grigorios Tsoumakas},
 keywords = {Multi-label learning, Class imbalance, Classifier chains, Undersampling},