diff --git a/README.md b/README.md
index 983a1de..ff6c1ba 100644
--- a/README.md
+++ b/README.md
@@ -5,4 +5,6 @@ comunication between two arduinos by software. It consumes about 300bytes less o
 than original. You can use the original one if you not define LITE in definitions part.
 Some functions removed too in this lite version like listen() and stopListening()
 because you can use only one serial comunication, end(), and peek(), and inverse logic.
-But they are in code, you can tweak it to include or not.
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+But they are in code, you can tweak it to include or not.
+
+Original code: https://github.com/arduino/Arduino/tree/master/hardware/arduino/avr/libraries/SoftwareSerial
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