Here's a way to identify primary sources in the DU and I-Share catalogs. This could mean the actual manuscripts (as in the paper that was written on in the 14th century) or published/edited documents (usually in book format published many year or centuries later.)
Look for the sub-heading - Sources in an item's list of topics, such as in the example below. "Sources" indicates the presence of primary documents.
Also, when reading other sources, you may come across references to primary documents. You can use the book catalogs to see if those documents are available.
When you see "Manuscript," such as in the results list image below, it usually means primary sources that cannot be checked out or requested from I-Share. These are usually items in Special Collections or Archives.
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