Using a reference to someone or something that is well known called?

A reference to someone or something that is well known is called an allusion.

Here are some other terms that might be used depending on the context:

* Citation: A direct reference to a specific source, often with a page number or other identifying information.

* Reference: A general term for any mention of something else, whether it's well known or not.

* Quotation: A direct reproduction of someone else's words.

* Metaphor: A figure of speech that compares two unlike things without using "like" or "as".

* Analogy: A comparison between two things that are similar in some way.

Let me know if you'd like to explore any of these concepts further!