diff --git a/code/cit.py b/code/cit.py
index c30498d1c6619a34650ff4b8a1b361cfaa699ed2..afc32716f3bd2eed60815942fa65136dc3732535 100644
--- a/code/cit.py
+++ b/code/cit.py
@@ -1,12 +1,30 @@
-import argparse
-import bibtexparser
-import re
+# Voraussetzungen
+#- Python 3.x
+#- bibtexparser (Installieren Sie es mit `pip install bibtexparser`)
 
 
 problemlist = []
 
 def main(): 
+
     print("Starting program...")
+    try:
+        import bibtexparser
+    except ImportError:
+        print("The package 'bibtexparser' is not installed. Install with: pip install bibtexparser")
+        exit(1)
+    try:
+        import argparse
+    except ImportError:
+        print("The package  'argparse' is not installed.")
+        exit(1)
+     try:
+        import re
+    except ImportError:
+        print("The package  're' is not installed.")
+        exit(1)
+
+
     try:
         #reading command line input and parsing it 
         parser = argparse.ArgumentParser(