tutorial-service-serial.md

@@ -100,3 +100,6 @@ To unlock a serial port after it has been initialized once you have to remove th
 ![image](/uploads/4cb2248780173b93b826e0527d81db3c/image.png)
 
 This error will also appear if you want to run two different FREDOSAR bundles (e.g. Enocean and Serial) on one Port or after stopping and restarting the Serial bundle.
+
+# Useful Links
+Raspberry Pi Serielle Schnittstelle: [Link Netzmafia](http://www.netzmafia.de/skripten/hardware/RasPi/RasPi_Serial.html)