Crediting and Licensing Your Sources
When you write a paper, you are expected to cite your sources. You need to provide information that uniquely identifies the item that you're citing so that someone else can track down it down themselves if they want to. And using a standard formula for doing this makes sure you include all the needed information, and that readers can interpret it. You can find basic information about the most common formulas on the library's citation guide.
When you are producing an artistic or theatrical work, an academic citation style might not make sense, but it's still up to you to find ways to be ethical in your use of sources and to give credit to others. If ideas, words, or designs were published less than 95 years ago, you may also need permission or to pay a licensing fee. Even when there's no legal protection for an idea, ethical creators collaborate with, credit, and compensate the creators they draw from. For more on the muddier aspects of copyright in theatrical contexts, see this article from American Theatre.