Korngold Collection in the Library of Congress
the updated version of the finding aid of the Erich Wolfgang Korngold Collection (Music Division, Library of Congress, Washington, D.C.) has been open to the public. This collection “consists primarily of holograph and copyist music manuscripts that span his entire compositional output, as well as sketches, fragments, libretti, and film cue sheets.” (from Collection Summary)
https://findingaids.loc.gov/exist_collections/ead3pdf/music/2020/mu020003.pdf