diff --git a/fet2020/intern/models.py b/fet2020/intern/models.py
index 70295346..57538c24 100644
--- a/fet2020/intern/models.py
+++ b/fet2020/intern/models.py
@@ -27,7 +27,8 @@ class TopicGroup(models.Model):
 
     class Meta:
         verbose_name = "Themenbereich"
-        verbose_name_plural = "Themenbereiche"
+        # "1." because this point should be displayed first in admin view.
+        verbose_name_plural = "1. Themenbereiche"
 
     def __str__(self):
         return self.title
@@ -61,7 +62,7 @@ class Topic(models.Model):
 
     class Meta:
         verbose_name = "Thema"
-        verbose_name_plural = "Themen"
+        verbose_name_plural = "2. Themen"
 
     def __str__(self):
         return self.title
@@ -86,6 +87,17 @@ class Documentation(models.Model):
 
     objects = models.Manager()
 
+    class Meta:
+        verbose_name = "Dokumentation"
+        verbose_name_plural = "3. Dokumentationen"
+
+        constraints = [
+            UniqueConstraint(fields=["slug", "topic"], name="unique_intern_slug_topic"),
+            UniqueConstraint(
+                fields=["title", "topic"], name="unique_intern_title_topic"
+            ),
+        ]
+
     def __str__(self):
         return self.topic.title + " / " + self.title
 
@@ -119,7 +131,7 @@ class Etherpad(models.Model):
 
         constraints = [
             UniqueConstraint(
-                fields=["title", "date", "documentation"], name="unique_intern_document"
+                fields=["title", "date", "documentation"], name="unique_intern_etherpad"
             ),
         ]