diff --git a/projekte/soundz/axelf/axelf.pde b/projekte/soundz/axelf/axelf.pde
index a5ec1c5..7c018e1 100644
--- a/projekte/soundz/axelf/axelf.pde
+++ b/projekte/soundz/axelf/axelf.pde
@@ -1,3 +1,6 @@
+// originally by Joby Taffey
+// http://chiphacker.com/questions/2057/polyphonic-sounds-from-a-microcontroller
+
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <avr/delay.h>