diff --git a/src/paveit/datamodels/material.py b/src/paveit/datamodels/material.py
index ed51fc0..268c349 100755
--- a/src/paveit/datamodels/material.py
+++ b/src/paveit/datamodels/material.py
@@ -33,7 +33,27 @@ class Material(Document):
                                  reverse_delete_rule=DO_NOTHING)
 
     tags = ListField(StringField())
-    norm = StringField(required=True, default='TP Asphalt Teil 24')
+    
+    def to_dict(self):
+        # convert data to dict
+        data = self.to_mongo().to_dict()
+
+        # Laden und hinzufügen der referenzierten Daten
+        try:
+            data['parameter'] = self.parameter.to_mongo().to_dict()
+        except:
+            pass
+        
+        try:    
+            norm = self.norm.fetch()  # Trigger the dereferencing
+            data['norm'] = norm.to_mongo().to_dict()
+        except:
+            raise    
+        
+        return data
+
+    
+
 
     meta = {
         'allow_inheritance': True,
@@ -73,19 +93,7 @@ class Bitumen(Material):
     parameter = ReferenceField(Material)
     limits = LazyReferenceField(EnumerateBase)
     
-    def to_dict(self):
-        # convert data to dict
-        data = self.to_mongo().to_dict()
 
-        # Laden und hinzufügen der referenzierten Daten
-        if self.parameter:
-            data['parameter'] = self.parameter.to_mongo().to_dict()
-            
-            
-        print(data)
-
-        # Konvertieren Sie das BSON-Dokument in ein Python-Dict
-        return data
     
 
 
@@ -125,6 +133,9 @@ class Aggregate(Material):
                                 required=True,
                                 reverse_delete_rule=CASCADE) #Lieferkörnung
     
+            
+    
+
 
 class Dummy(Material):