Attributed to Charles Joseph Sax – Cor omnitonique – Belgian – The Metropolitan Museum of Art https://www.metmuseum.org/art/collection/search/503956?exhibitionId=%7Ba427663c-7533-4867-9794-2a5fac26eca4%7D&oid=503956&pkgids=280&pg=1&rpp=4&pos=4&ft=*&locale=en
Catalogue of the Crosby Brown Collection of Musical Instruments of All Nations: I
