diff --git a/README.md b/README.md
index 6892114..9663cb1 100644
--- a/README.md
+++ b/README.md
@@ -5,6 +5,6 @@ After learning the basics of looking up IP addresses, domain names and URLs to f
 ## TODO
  - *TD* - Strip leading and trailing characters like parentheses, brackets, etc. and extract host information
  - *TD* - Reorganize the windows to have one window for extracting hosts and reformatting (adding comma's, quotes, etc.) and one window for lookup information
- - *TD* - Rewrite the code to use classes for window and their functions (f.e. https://stackoverflow.com/a/17466924)
+ - *TD* - Rewrite the code to use classes for window and their functions (f.e. https://stackoverflow.com/a/17466924 and continue here https://www.digitalocean.com/community/tutorials/tkinter-working-with-classes)
 - *TD* - Try to create a copy-paste button: https://www.delftstack.com/howto/python/python-copy-to-clipboard/#copy-text-to-clipboard-in-python-using-the-tkinter-module, https://stackoverflow.com/a/71357987
 - *D* - Instead of a label showing the output, use a text box: https://pythonguides.com/python-tkinter-text-box/