Update app.py

app.py

@@ -95,7 +95,7 @@ if uploaded_file is not None:
     
         #===Visualization===
         if 'Publication Year' in data.columns:
-                   papers.rename(columns={'Publication Year': 'Year', 'Citing Works Count': 'Cited by',
+                   data.rename(columns={'Publication Year': 'Year', 'Citing Works Count': 'Cited by',
                                          'Publication Type': 'Document Type', 'Source Title': 'Source title'}, inplace=True)
     
         col2check = ['Document Type','Source title','Cited by','Year']