diff --git a/letters/admin.py b/letters/admin.py
index f1356df..b827bda 100644
--- a/letters/admin.py
+++ b/letters/admin.py
@@ -114,7 +114,7 @@ class MiscDocumentAdmin(DocumentAdmin):
 
 class PlaceAdmin(gisAdmin.OSMGeoAdmin):
     # show Save and Delete buttons at the top of the page as well as at the bottom
-    save_on_top=True
+    save_on_top = True
     fields = ['id', 'name', 'state', 'country', 'point', 'notes']
     readonly_fields = ['id']
     default_lon = -8635591.130572217
diff --git a/letters/admin_filters.py b/letters/admin_filters.py
index b89132b..652906b 100644
--- a/letters/admin_filters.py
+++ b/letters/admin_filters.py
@@ -23,8 +23,7 @@ def get_objects_with_date(model):
 
 
 def get_source_lookups():
-    sources = set([doc_source for doc_source in DocumentSource.objects.all()])
-    return [(source.id, source.name) for source in sources]
+    return DocumentSource.objects.values_list('id', 'name')
 
 
 # Get all Correspondents associated with a particular DocumentSource