Music Primary Sources 

RISM B/IV (Manuscripts of Polyphonic Music, 11th - 16th Cenuturies): Includes entries of all known polyphonic manuscripts beginning in the Ars Nova period. Each piece is cataloged with an incipit and description. (Music Ref ML113 .I6 Ser. B v. 4, pts. 1-5, and suppl.)

Census-Catalogue of manuscript sources of polyphonic music, 1400-1550 : Includes entries for all known manuscript sources of polyphonic music in mensural notation for the period 1400-1550; arranged alphabetically. (Music Ref ML135.C46 v.1-5)

RISM B/III: The Theory of Music.  Manuscripts of music theory treatises from the Carolingian Era up to 1400.  Arranged geographically. Ref Is. M113 .I6 Ser. B v. 3, pts. 1-6

There is no single source to find music manuscripts of world.  The major sources are:

- RISM A/II (Music Manuscript from 1600-1850):  Online catalog of music manuscripts

- Census-Catalogue of Manuscript Sources of Polyphonic Music, 1400-1550: 5 printed volumes of ms. (ML135 .C46 v. 1-5, Music Reference)

- RISM B/IV (Music Manuscripts from 11th to 16th Centuries): Printed catalog in 5 parts.  (ML113 .I6 Ser. B v. 4, pt. 1-5 and suppl.)

- New Grove Dictionary of Music and Musicians -- the article "Sources. Ms." This article includes a list of music manuscripts from the 9th century until the Renaissance, arranged by chronological periods and then alphabetically by cities. REF Is. ML100 .N48 2001 v. 23 or online

RISM A/II (Music Manuscripts from 1600-ca. 1850) A comprehensive annotated index and guide to music manuscripts produced after 1600. The database has more than 585,559 records by over 20,500 composers and is linked to three other databases providing additional information to specific content: Composer, Library Sigla and Bibliographic Citations. [UW restricted]

Most of these links will allow access to music and other manuscripts.  Music Manuscripts link will be thus specified:

United Kingdom:

Cecilia Project -- Finding music collections (archives included) in the UK http://www.cecilia-uk.org/

British Library Manuscript Catalogue -- http://molcat.bl.uk

Italy:

Italian National Manuscripts -- http://www.braidense.it/urfm/)

Italian music manuscripts through this web site: http://opac.sbn.it/opacsbn/opac/iccu/musica.isp  After the search, you can filter for music manuscripts.

United States:

National Union Catalogue of Manuscripts (NUCMC) -- http://www.loc.gov/coll/nucmc/