diff --git a/input/models.py b/input/models.py
index 6f42c34..b798ef8 100644
--- a/input/models.py
+++ b/input/models.py
@@ -39,9 +39,9 @@ class Extern(Volunteer):
 
     def save(self,*args,**kwargs):
         # is there a way to call super().save() only once?
-        super().save(*args,**kwargs)
+        super().save()
         self.service_id = type(self).__name__ + str(self.pk)
-        super().save(*args,**kwargs)
+        super().save()
 
     class Meta:
         abstract = True
diff --git a/input/tests.py b/input/tests.py
index 86a2e1e..7f8d9bc 100644
--- a/input/tests.py
+++ b/input/tests.py
@@ -3,7 +3,7 @@ from django.conf import settings
 from django.contrib.auth.models import User
 from datetime import date
 
-from .models import HonoraryCertificate, Project, Account
+from .models import HonoraryCertificate, Project, Account, Literature
 
 class TestWithoutLogin(TestCase):
 
@@ -85,6 +85,7 @@ class TestWithLogin(TestCase):
         startdate = date(2022,1,1)
         obj = Project.objects.create(account= acc, name='testproject', start=startdate)
         self.assertEqual(obj.pid,"1234001")
+        self.assertEqual(obj.account.code,"1234")
 
         obj2 = Project.objects.create(account= acc, name='testproject2', start=startdate)
         self.assertEqual(obj2.pid,"1234002")
@@ -94,3 +95,7 @@ class TestWithLogin(TestCase):
 
         obj3 = Project.objects.create(account= acc, name='testproject2', start=startdate)
         self.assertEqual(obj3.pid,"1234004")
+
+    def test_literature(self):
+        obj = Literature.objects.create(cost='100', notes='jolo')
+        self.assertEqual(obj.service_id,'Literature1')