Citing a primary source document, from an archives, varies depending on the preference of your instructor, the publication you are submitting the article, or the discipline in which you are operating. The particular style may be the American Psychological Assocaition (APA), the Modern Language Association (MLA), the Chicago Manual of Style, etc.
There are several elements to the citation which may be necessary to properly cite a document.
The document: The creator or author, specific item title, page, section, date.
Box and file number: The majority of unpublisged materials found in archives are housed in some sort of container and within the container items are organized in file folders.
Repository: This is the name of the archives.
Citing a digital object: The ..., is found online ...in ... It is both a paper document in the collection and a digital object in .... The best way of citing this document as a digital object using one of the above formats, APA, MLA, or Chicago Manual of Style is to add the Reference URL at the end of the citation.