"RISM" stands for Repertoire International des Sources Musicales. It's an ongoing scholarly project to catalog all the primary source materials, in libraries worldwide, relating to music. It gives detailed descriptions of music manuscripts, early printed editions of music, and early treatises on music.
Here you find RISM’s vast collection of musical sources and can freely search among 700,000 entries that contain mostly historical music manuscripts (the majority originated before 1800).The original sources are available from the libraries, music archives, and private collections as indicated in the RISM database. These institutions can often be approached for reproductions.
You can search RISM here: http://opac.rism.info/index.php?id=2&L=1
Series A/1
Printed music before 1800
Call no.: Ref ML113 I6 vol.A/1
Series A/2
Manuscripts after 1600
Online (Library's hompage, R under "Databases", RISM)
Series B
Manuscripts of polyphonic music, 11th-16th centuries
Printed collections of music, 16th-17th centuries
Early treatises on music
Call no.: Ref ML113 I6 vol.B
Series C
Directories of libraries that own primary source materials for music
Call no.: Ref ML113 I6 vol.C
For any given manuscript, you can expect to see the folowing data in RISM:
Description of the manuscript
Text incipit, music incipit (first line of text, first few bars of the music)
Brief bibliography (articles about this manuscript)
Library that owns the manuscript (abbreviations are used; see the library's full name in the list at the front of the volume)
For any early printed edition of a musical work, you can expect to see the following data in RISM:
Bibliographic citation (including a full transcription of the original tite page)
Libraries that own a copy of the edition (abbreviations are used; see the libraries' full names in the list at the front of the volume)
RISM entry number (you may see this number included in other authors' citations of this edition)
The individual volumes of RISM have been published variously in English, German, and French. Here are some common terms you will see in RISM, with their German and French equivalents:
Manuscript
Abbreviation: MS (singular), MSS (plural)
German: Handschrift (abbreviation.: Hs.)
French: manuscrit
Collection
German: Sammlung
French: recueil
Folio
Term used for the leaves/pages of a manuscript.
Abbreviation: f.
Edition
German: Ausgabe (abbreviation: Ausg.)
French: edition
Editor
German: Herausgegeber
French: redacteur
Publication, Printing
German: Druck
French: imprime
Publisher
German: Verlag
French: editeur
Library
German: Bibliothek. (Bibliotheksigel = library's symbol used in RISM)
French: bibliotheque