Published primary sources include autobiographies, newspapers and pamphlets--anything that was produced in a formalized way and distributed for public consumption. For the purposes of citation, this also includes things like letters and diaries that, while originally created as private, unpublished manuscripts, have since been published in a book or periodical for anyone to read. Anne Frank: The Diary of a Young Girl or The Selected Letters of Mark Twain are examples of such publications.
Unpublished primary sources include things like personal papers, letters, diaries, and manuscripts that have not been formally published. These are the materials that will require a bit more thought and digging in order to construct a citation.
Remember how primary source citations are like a street address? It's time to think about where you found your source. If you found it in a library database, through an online source like Google Books, or in a published format, follow your citation style's guidelines for referencing those types of sources.
If your source comes from a specific archival repository, this is where you will need to include that information. Consult the repository's website, the finding aid for the collection, or the webpage for the specific document to learn how they want you to cite the repository itself, as well as the location of the collection within the repository.
Note that some published sources will still require that you cite repository information. For example, you might find an original copy of a 200-year-old published pamphlet in an archives. While the contents of the pamphlet itself can be cited as though it were a work published yesterday, you will still want to cite the archives where you found it, so that other researchers could find it. However, if you found the text of the pamphlet published in a book that circulates at your local library, you would not need to cite the library itself, just the publication information for the book.
If the repository that owns your unpublished primary source provides a preferred citation, use that whenever possible. If necessary, make adjustments so that it reflects the formatting of your assigned citation style.
If a preferred citation is not available, or if your professor will only accept the assigned citation style (APA, MLA, Chicago/Turabian, etc.), then it's time to roll up your sleeves and construct a citation that satisfies the requirements. First, check to see if your assigned style has guidelines for citing manuscript collections. If not, think about the general format that your style uses--are there periods, commas, or semicolons between each element? Does access information usually come before or after things like title and author? You can use these rules to extrapolate how your primary source citation should look.
Next, think about how the information you need to include about your unpublished source corresponds to the information required by your assigned citation style. If there aren't specific guidelines for manuscript collections, can you pull out any information like a title, author, or date in order to construct your own citation?
Finally, decide how you can include any necessary access or repository information in a way that conforms to your assigned citation style. For example, the Chicago Manual of Style guidelines for manuscript collections specifically provide for the inclusion of a repository name and location. If your citation style does not have similar guidelines, include the information at the end of the citation, where you would normally place access information like a URL.
When in doubt, consult your professor or the staff of the Norwich University Archives, who prepared this guide for you. Good luck!