diff --git a/Database.py b/Database.py
index 9e8741c..588de11 100644
--- a/Database.py
+++ b/Database.py
@@ -1,3 +1,8 @@
+# Reference: Database Using Python Pandas
+# https://www.youtube.com/watch?v=_nYbrut66cc
+# Reference: Miscellaneous operating system interfaces
+# https://docs.python.org/3/library/os.html
+
 import pandas as pd # to manipulate data in .csv format
 import os # to create directories and check their existence