I'm writing an essay for school, and I would like to open with a quote, but the quote is by an anonymous person?

I'm writing an essay about Alcatraz Prison, and I would like to open with the quote, "Break the rules and you go to prison, break the prison rules and you go to Alcatraz." But the quote is by an unknown person. Was wondering if there was a certain way to introduce this quote or not.
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