Piano samples from tonejs-instruments by N. P. Brosowsky
https://github.com/nbrosowsky/tonejs-instruments
License: Creative Commons Attribution 3.0
https://creativecommons.org/licenses/by/3.0/
Selected MP3 samples are bundled unchanged as base64; playback transposes nearby samples when required.

Original source information:
bass        - Karoryfer
bassoon     - VSO2
cello       - Freesound - 12408__flcellogrl__real-cello-notes
contrabass  - VSO2
flute       - VSO2
french horn - VSO2
guitar ac   - Iowa
guitar el   - Karoryfer
guitar ny   - Freesound - 11573__quartertone__classicalguitar-multisampled
harmonium   - Freesound - 330410__donyaquick__harmonium-samples-all-keys-and-drones
harp        - VSO2
organ       - VSO2
piano       - VSO2
sax         - Karoryfer
trombone    - VSO2
trumpet     - VSO2
tuba        - VSO2
violin      - VSO2
xylophone   - VSO2


https://freesound.org
https://www.karoryfer.com/karoryfer-samples
http://vis.versilstudios.net/vsco-community.html
http://theremin.music.uiowa.edu/