Citing Sources within Your Document (Using In-Text Numbering)
The CMS - Notes in-text citation system is simple: It relies on numbers. Unlike the MLA and the APA, no parenthetical information is required. All that's needed is a superscripted number: a raised numeral located at the end of a clause or sentence identifying the content as outside source material.
The superscripted number flags the reader's attention to the existence of a citation note bearing the same number located either at the bottom of a page or the end of a book or document.