Crediting third party rights holders, authors, and creators
You must include full citations for all copyright material in your dissertation regardless of author or source.
The style guide you are following for your dissertation, including citation style, will lead you but at a minimum each citation must include the copyright symbol © or Copyright, the name of the copyright owner (who may or may not be the author or creator), and specific page or other relevant references.
If you have adapted or modified another’s work with their permission, the source credit should include the author/title of the original figure and that the material has been adapted with permission, e.g. “Adapted from…” and “Reproduced with the permission of…”.
If you obtain permission to include an item you will need to credit the copyright holder at the appropriate place in your thesis and state that clearance was obtained, e.g. ‘Permission to reproduce this [detail of content] has been granted by [rights holder information].’ If you establish that no clearance is required, for example if an item in out of copyright you should include a credit to the creator, for example 'Leonardo da Vinci, Mona Lisa - out of copyright'.
If permission is not granted and you are still researching your thesis, you can attempt to find another item to replace the uncleared content or if you prefer, you can redact the item and provide a redacted version of your thesis which can be made open access.