diff --git a/ippisite/ippidb/models.py b/ippisite/ippidb/models.py
index 66dcac113ded49202ea6fc28a8797f19df35daaf..fd6d9bde378e61d93b5d2a5d3c6f360e381fc10b 100644
--- a/ippisite/ippidb/models.py
+++ b/ippisite/ippidb/models.py
@@ -1280,7 +1280,9 @@ class CompoundActivityResult(models.Model):
 
     @property
     def ref(self):
-        return RefCompoundBiblio.objects.get(compound=self.compound, bibliography=self.test_activity_description.biblio)
+        return RefCompoundBiblio.objects.get(
+            compound=self.compound, bibliography=self.test_activity_description.biblio
+        )
 
 
 class TestCytotoxDescription(models.Model):
@@ -1321,7 +1323,10 @@ class CompoundCytotoxicityResult(models.Model):
 
     @property
     def ref(self):
-        return RefCompoundBiblio.objects.get(compound=self.compound, bibliography=self.test_cytotoxicity_description.biblio)
+        return RefCompoundBiblio.objects.get(
+            compound=self.compound,
+            bibliography=self.test_cytotoxicity_description.biblio,
+        )
 
 
 class TestPKDescription(models.Model):
@@ -1384,7 +1389,9 @@ class CompoundPKResult(models.Model):
 
     @property
     def ref(self):
-        return RefCompoundBiblio.objects.get(compound=self.compound, bibliography=self.test_pk_description.biblio)
+        return RefCompoundBiblio.objects.get(
+            compound=self.compound, bibliography=self.test_pk_description.biblio
+        )
 
 
 class CompoundAction(models.Model):