However, these notes can also be used to expand on ideas in the text.
If the notes are located at the bottom of each page, they're called footnotes; if they're collected at the end of the paper, they're called endnotes.
Among the most important of these style challenges are footnotes, which historians rely on more than scholars in any other field.
edition of The Chicago Manual of Style, which is the most common style guide used for works in history.
When you do need to cite the same source more than once, you can use a shortened version of the bibliographic entry.
If you're citing the same source in two footnotes in a row, you can use the abbreviation ibid with the page number.
In this article I'm going to refer to footnotes only, but all the issues discussed below can be applied to endnotes as well.
What to cite: Deciding what material to cite can be tricky.
See our section on citation styles for more information.
Footnotes are not just for interesting comments, however.