diff --git a/Compile-andriod-kernel-for-cm4.md b/Compile-andriod-kernel-for-cm4.md
index ba184dd..752219d 100644
--- a/Compile-andriod-kernel-for-cm4.md
+++ b/Compile-andriod-kernel-for-cm4.md
@@ -47,3 +47,7 @@ sudo umount /mnt/p1
 sudo losetup -D /dev/loop0
 
 ```
+
+#  Reference Url
+* https://github.com/android-rpi/kernel_manifest
+* https://github.com/android-rpi/device_arpi_rpi4
\ No newline at end of file