Copyright Guide for Thesis Preparation
How to seek permission to include copyrighted works in your thesis - When to Seek Permission
If, after reading about copyright and consulting with your thesis committee, you consider that your thesis includes elements (text, graphs, tables, images, etc.) that are substantial and do not constitute fair dealing, then you must seek permission to reproduce them. This applies to both materials from other authors and your own materials that have been previously published.
As obtaining an official letter or signed form from the copyright holder can take time, you will want to seek permission early in the thesis process, especially if you need to contact multiple publishers.