diff --git a/graphs/array_to_graph.py b/graphs/array_to_graph.py
index c90a45617..e22b5dac1 100644
--- a/graphs/array_to_graph.py
+++ b/graphs/array_to_graph.py
@@ -1,7 +1,29 @@
 """
-Reference: https://gist.github.com/harigro/28df9ec639f74f217473f85065acf9d8
+MIT License
+
+Copyright (c) 2024 yuhari
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
 """
 
+# https://gist.github.com/harigro/28df9ec639f74f217473f85065acf9d8
+
 
 def divide_array_to_graph(arr: list[int], base: int) -> dict[int, list[int]]:
     """