De Ricci numbers

Title page of Seymour de Ricci's manuscripts census

Many manuscripts in the Folger collection are known by their "de Ricci" numbers, as well as by their Folger call numbers. De Ricci numbers come from Seymour de Ricci, Census of medieval and renaissance manuscripts in the United States and Canada. New York : H. W. Wilson, 1935-1940, and are based on Folger case numbers and accession numbers.

The Folger has several bound copies of de Ricci's three-volume census (catalog record).

A searchable scanned copy of the census is available as an ACLS Humanities E-book (access restricted by licensing agreement):

In the catalog

To find manuscripts by de Ricci number in the Folger Catalog, you can type "citation:" in the search box, followed by the Standard Citation Form for the publication and the reference number, in quotation marks. For example:
citation:"Ricci, S. de. Census of medieval and Renaissance manuscripts in the United States and Canada, 1.61"

That being said, you'll probably get the record you want just by searching the "citation" index for the keyword "Ricci" and the reference number. For example:
citation:("Ricci" AND "1.61")

Ricci citation search example.png