The BNF has recently converted its card catalogues of the library’s music collections. The 560,584 converted records may be searched and displayed in the online General Catalogue of the Library. This means the earlier collections (manuscript and printed music, treatises, methods, critical works, archives, programs, newspaper cuttings), added to the library between the 16th century and 1991, can now be searched online at http://catalogue.bnf.fr.
An important counterpart to this is the immense digital library offered by the BNF’s Gallica which offers nearly 2 million digitised documents, including 10,000 scores from its collections. Gallica’s digitised music collections can be found at http://gallica.bnf.fr/html/editorial/partitions. (Follow the link Découvrir le fonds des partitions on the bottom of the webpage).