De Ricci numbers
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.
A searchable scanned copy is available as an ACLS Humanities E-book (access restricted by licensing agreement):
- Volume 1: Alabama - Massachusetts (Folger Shakespeare Library entry starts on page 267)
- Volume 2: Michigan - Wisconsin, Hawaii, Canada
- Volume 3: Indexes
To find manuscripts by de Ricci number in Hamnet, do an Advanced Search of the "Bibliographic citation" field in Hamnet: search for "Ricci" and "Medieval" in one box, and the number as a phrase in another box (NB. because the number includes a decimal, it's necessary to search it "as a phrase" or it will be interpreted as two numbers).