Chicago style is especially popular in historical research.
When developing a historical explanation from multiple primary sources, using footnotes instead of inserting parenthetical information allows the reader to focus on the evidence instead of being distracted by the publication information about that evidence.
There are many styles of referencing; the two most common systems are Harvard and Numeric. In the text use the surname(s) of the author(s) and the year of publication.
References should then be listed alphabetically by author at the end of the work, with the year of publication placed immediately after the author's name.
See Signaling Sources in the Body of Your Paper for more information.
Note: Some works written with MLA or APA style also include what are called discursive footnotes.
Academic disciplines have varying expectations for how to list citation information.
In some instances, even two journals in the same field will use different styles.
In the Numeric system of referencing, numbers inserted in the text refer to a numerical sequence of references at the end.
The first reference is numbered 1, the second 2, and so on.