In general, we cite sources for two main reasons: to acknowledge the creator of the content (words, ideas, images, etc.) we have used in our work, and to point our audience to the source so they can access it for their own use. Of course, generative AI such as ChatGPT provides different content with each prompt, so recreating the same content is at best unlikely if not impossible. But we can at least acknowledge a specific AI tool as a source of content we have used. Adding an explanatory footnote or brief explanation in a "methods" section can be helpful to outline how a tool was used.

Official citation styles for AI are still being created and will likely evolve, but here are some current examples:
 

APA Style

• in-text citation:
  (OpenAI, 2023)
• reference in bibliography: 
  OpenAI. (2023). ChatGPT (Mar 14 version) [Large language model]. https://chat.openai.com/chat

Chicago Manual of Style

• A parenthetical remark in the text may suffice as an acknowledgement (this text was generated by ChatGPT), but for a more formal citation you can use a footnote:
  1. Text generated by ChatGPT, OpenAI, March 7, 2023, https://chat.openai.com/chat.
       or
  2. ChatGPT, response to “Explain how to make pizza dough from common household ingredients,” OpenAI, March 7, 2023.

MLA Style

• MLA is more flexible and adaptable, so see their page on citing AI for specifics.
• One possible format: add a parenthetical remark in your text ("Describe the symbolism") to refer to the citation in a "works cited" list:
  "Describe the symbolism of the green light in the book The Great Gatsby by F. Scott Fitzgerald" prompt. ChatGPT, 13 Feb. version, OpenAI, 8 Mar. 2023, chat.openai.com/chat.