From CMOS website:
Q. How do you recommend citing content developed or generated by artificial intelligence, such as ChatGPT? Many scholarly publishers are requiring its identification though also requiring human authors to take responsibility for it and will not permit the AI to have “authorship.”
A. You do need to credit ChatGPT and similar tools whenever you use the text that they generate in your own work. But for most types of writing, you can simply acknowledge the AI tool in your text (e.g., “The following recipe for pizza dough was generated by ChatGPT”).
If you need a more formal citation—for example, for a student paper or for a research article—a numbered footnote or endnote might look like this:
1. Text generated by ChatGPT, OpenAI, March 7, 2023, https://chat.openai.com/chat.
ChatGPT stands in as “author” of the content, and OpenAI (the company that developed ChatGPT) is the publisher or sponsor, followed by the date the text was generated. After that, the URL tells us where the ChatGPT tool may be found, but because readers can’t necessarily get to the cited content (see below), that URL isn’t an essential element of the citation.
If the prompt hasn’t been included in the text, it can be included in the note:
1. ChatGPT, response to “Explain how to make pizza dough from common household ingredients,” OpenAI, March 7, 2023.