"Chicago" style offers writers a choice of several different formats. It allows the mixing of formats, provided that the result is clear and consistent. For instance, the 15th edition of "The Chicago Manual of Style" permits the use of both in-text citation systems and/or footnotes or endnotes, including use of "content notes"; it gives information about in-text citation by page number (such as MLA style) or by year of publication (like APA style); it even provides for variations in styles of footnotes and endnotes, depending on whether the paper includes a full bibliography at the end.