Copyright Guide for Thesis Preparation
How to seek permission to include copyrighted works in your thesis - Proof of permission
Keep all correspondence (emails, letters, forms) exchanged with copyright holders. Do not include these documents in your thesis but keep them in your files as they constitute proof that you have obtained permission to use the copyrighted materials.
In your thesis, each time you use material for which you have obtained reproduction rights, you should include a statement such as “reproduced with permission from XYZ.”