"Documentation is not required for every type of borrowed material. Information and ideas that are common knowledge among your readers need not be documented. Common knowledge includes information widely available in reference works, such as basic biographical facts about prominent persons and the dates and circumstances of major historical events. When the facts are in dispute, however, or when your readers may want more information about your topic, it is good practice to document the material you borrow" (10).
MLA Handbook. 8th ed., Modern Language Association of America, 2016