By default, the source editing information is arrange to record “manuscript” type sources, i.e. those that exist in original form, often in an archive. It is always advised to check these “original” documents (or surrogates) where possible. However, sometimes the only source might be published information. Perhaps you can’t access the original, or it might have even been destroyed and so information published whilst the original still existed is the only source.
Published sources such as this are better described with an author and date of publication, rather than an archive and call number. This can be entered in the “More Options” section of the source panel. If the fields aren’t showing, you may need to click on the “>” button to show the fields:
The “Published” field would normally be the place and year of publication.