MLA style (named for the Modern Language Association of America which developed it) is most frequently used in the study of literature, but is also occasionally used in the study of history as well. The basic elements of MLA-style citation include in-text citations, either parenthetical or embedded in the running text, with a list of Works Cited collecting these references appended to the end of the document.
The most recent MLA standard defines MLA "core elements," facts common to most source materials. These core elements include author, title, date of publication, volume or number, etc. For a visual guide to these core elements and a template for creating citations, see Fig. 5.1 of the MLA handbook online.
Fig. 5.1 MLA Core Elements, MLA Handbook Ch. 05, 9th edition.
The MLA standard uses a system of "containers" to develop citations. For example, when citing an article published in a journal, the title of the journal (Nature, The Lancet, etc.) would be the "container" of the article in question. This logic is well suited to citing archival sources because it allows for flexibility in the types of sources cited while maintaining a consistent structure for each citation. As an example, a letter, memorandum, or other document in an archival collection would be an object "contained" within the collection
Formatting MLA-style citations of archival material is relatively straightforward. Using the MLA core elements template, we simply slot each piece of information into its corresponding section of the template.
Example:
Prince, W.B., Letter to Judge R. H. Hanna. 08 March 1940. Richard H. Hanna Papers (MSS 762 BC, box 8, folder 31), Center for Southwest Research, University Libraries, University of New Mexico. Manuscript.
Note that in some cases archival materials may not have listed authors. In this case, the citation would begin with the title or description of the archival object.