Just as you need to properly cite others' ideas in your thesis body text, you should include citations in the executive summary if needed and a short List of References at the end.

What is included in an executive summary?

What is included? An executive summary should summarize the key points of the report. It should restate the purpose of the report, highlight the major points of the report, and describe any results, conclusions, or recommendations from the report.

Do I need to cite when writing a summary?

As you write your summary, you will want to remind your reader, occasionally, that you are still summarizing. You can do this simply be referring back to the authors, the title of the article, or both. Remember, however, that anything that needs an APA in-text citation will need to refer to author and date.