diff --git a/README.md b/README.md
index a6aa3fe..f1e7113 100644
--- a/README.md
+++ b/README.md
@@ -100,4 +100,9 @@ in short, if mask[i][j] == [1, 2, 4], this point can change
    ```py
    from Qart import Image
    img.show("OTSU")
-   ```
\ No newline at end of file
+   ```
+
+## Reference
+
+1. [QArt Codes](https://research.swtch.com/qart)
+2. [thonky](https://www.thonky.com/qr-code-tutorial/)