diff --git a/docs/conf.py b/docs/conf.py
index dd86a87a6..630948655 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -75,5 +75,6 @@ def setup(app):
     r"https://forum.openmod-initiative.org/*",
     r"https://github.com/oemof/oemof-solph/issues/*",
     r"https://github.com/oemof/oemof-solph/pull/*",
-    "https://www.sciencedirect.com/science/article/abs/pii/S036054421500331X",  # 403 in CI pipeline
+    # Due to traffic limitation, the folowwing creates a 403 in CI pipeline:
+    "https://www.sciencedirect.com/science/article/abs/pii/S036054421500331X",
 ]