diff --git a/pro_micro/pro_micro.ino b/pro_micro/pro_micro.ino
index 676188e..3e1b207 100644
--- a/pro_micro/pro_micro.ino
+++ b/pro_micro/pro_micro.ino
@@ -1,6 +1,6 @@
 /* Pro Micro Test Code
 
-Code von https://codebender.cc/sketch:77845#Pro%20Micro%20Blink.ino
+Code von https://codebender.cc/sketch:77845#Pro%20Micro%20Blink.ino (Blinken) und https://www.instructables.com/id/Arduino-Programmable-Button-Panel-As-Keyboard/ (Button)
 Zuerst musste unter Ubuntu der Modem Manager entfernt werden mit, s. https://community.arduboy.com/t/resolved-issues-uploading-with-ubuntu-18-10-and-arduino-1-8-9/7447/4
   sudo systemctl disable ModemManager.service
 
@@ -20,6 +20,7 @@ Troubleshooting, wenn bricked:
     sudo ./arduino --upload /root/Arduino/pro_micro/pro_micro.ino --port /dev/ttypACM3
 
 Auch hilfreich:
+  ls /dev/input/by-id/
   ls /dev/ttyA*
   lsusb