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Helpful Chicago Style Guides 18th Edition:
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Citing Generative AI in Chicago 18th Edition
Last updated July 23, 2025
Please check with your professor to know whether generative AI is allowed for the assignment. This information can be found in your course syllabus.
All citation styles require you to cite generative AI when it is used in your research or writing. Below are some guidelines and examples:
Chicago Author-Date Citations
Chicago Author-Date considers the tool as the author, and the date the content was generated should be used as the date. Additionally, it's important to state how the tool was used; a summary is ok in the case of a longer conversation.
General format: Response to "prompt," publisher/developer, date when content was generated, URL.
Examples:
The following explanation for rising ocean acidification levels was generated on July 16, 2025 by ChatGPT-4o.
One explanation for rising ocean acidification levels is as follow (ChatGPT-4o, July 16, 2025).
Notes & Bibliography (footnotes & endnotes)
If the prompt is not included in the text, in needs to be included in a footnote/endnote; a summary is ok in the case of a longer conversation.
General format for a footnote/endnote: Text generated by name of tool, publisher/developer, date, URL.
- Name of tool: name of software used.
- Publisher/developer: the publisher/developer of the tool (ex: OpenAI).
- Date: the date the content was generated.
- URL: a publicly available URL. You can create this using the share button available with many generative AI tools.
Examples:
1. Text generated by ChatGPT-4o, OpenAI, July 16, 2025, https://chatgpt.com/share/68795492-078c-8006-ac76-79dd427a8532.
2. Text generated by Perplexity, Perplexity AI, May 24, 2025, https://www.perplexity.ai/search/what-version-of-perplexity-is-b4kae9aKSeCc46JWytawLg#0.
Bibliography
The official stance of the CMOS is that generative AI is not usually listed in a bibliography. However, it is likely your professors will expect you to cite it. Please refer to your syllabus for individual course policies.

General format: Publisher/developer. Response to "prompt." AI model and version, date, URL.
- Publisher/developer: the publisher/developer of the tool (ex: OpenAI).
- Response to "prompt": (ex: Response to "Explain the science of fire ecology.").
- AI model and version: use the version of the tool as listed by the author/developer. Chat tools based on ChatGPT use the month and day accessed as the version (ex: July 14 version). Other chat tools may use a different naming system (ex: v4.0.0).
- Date: the date the content was generated.
- URL: a publicly available URL. You can create this using the share button available with many generative AI tools.
Examples:
OpenAI. Response to "Explain the rising acidification levels of the world's oceans." ChatGPT-4o, July 16, 2025. https://chatgpt.com/share/68795492-078c-8006-ac76-79dd427a8532.
Perplexity AI. Response to "Can you list the major harms of rainforest deforestation?" v4.0.0, July 16, 2025. https://www.perplexity.ai/search/can-you-list-the-major-harms-o-EslYpEabQ.KRy9ivJhcstw.
Examples adapted from CMOS guide: https://www.chicagomanualofstyle.org/book/ed18/part3/ch14/psec112.html