Click the link for "Advanced Search," at the bottom left of the box.
Enter keywords and select "Music Scores" from "Format" drop-down menu)
For cataloged scores, call number and/or location information vary according to when it was cataloged. More recently cataloged scores have traditional Library of Congress call numbers that begin with "M". In both the current and previous systems, scores are also categorized by type: Choral, Vocal, Instrumental, and Study Score; your search results may include a mix of records reflecting location information from both systems.