Which style should I use?
Use Chicago Style for Business, History, and Fine Arts.
Use APA (American Psychological Association) Style for Education, Psychology and Sociology, and sciences.
Use MLA (Modern Language Association) Style for humanities (English, Philosophy, etc.)
In the notes, cite the individual item, the date, identifier if there is one, collection name, and name and repository of the collection.
For example, a footnote might look like this:
1. Correspondence from Olive Higgins Prouty to Lewis Prouty, 21 January 1919, Box 6, Folder 1, Olive Higgins Prouty Papers, Archives and Special Collections at Clark University, Worcester, MA.
Separate primary source materials and secondary source materials with section headers.
If you are citing more than one item from an archival collection, cite the collection as a whole: Collection name. Repository, location.
Robert H. Goddard Papers. Clark University Archives and Special Collections, Worcester, MA.
If you are citing one item from a collection, cite only the individual item:
Prouty, Olive Higgins. Correspondence from Olive Higgins Prouty to Lewis Prouty. 21 January 1919. Box 6, Folder 1. Olive Higgins Prouty Papers. Archives and Special Collections, Clark University, Worcester, MA.
APA style uses Parenthetical or Narrative style in-text citations, depending on whether the citation is all at the end of the statement, or incorporated into the text of the article. Cite archival material as you would other material, using the author and date.
Parenthetical: (Goddard, 1920)
Narrative: Goddard (1920)
If only one item from a collection is cited, list the specific item:
Goddard, R. H. (1920 [Letter from R.H. Goddard to E.E. Aldrin]. Robert H. Goddard Papers (Box 2-1-3), Archives and Special Collections, Clark University, Worcester, MA, United States.
If multiple items from a collection are cited, list the collection:
Goddard, R. H. (1920). [Letter from R.H. Goddard to E.E. Aldrin]. Archives and Special Collections (Robert H. Goddard Papers, Box 2-1-3), Clark University, Worcester, MA, United States.
MLA uses the author, date format for in-text citations. That means that in the text of the article or essay, you will record the author and date in a way that will differentiate this source from others in your bibliography. This usually appears at the end of the sentence in parentheses (parenthetical citation). Here are two examples:
(Carroll Wright, "The Results of the Massachusetts Public School System", 1879).
In your works cited page, you will need to list the full citation for each item you have cited. For example:
Wright, Carroll. "The Results of the Massachusetts Public School System," January 7, 1879. Papers of Carroll D. Wright, Archives and Special Collections, Clark University, box 2-3-2, folder 18.