https://www.pdinfo.com/royalty-free-music.php
http://www.openmusicarchive.org/
https://www.lifewire.com/public-domain-music-3482603
https://freesound.org/browse/tags/
https://pixabay.com/music/search/public%20domain%20music/
https://www.freemusicpublicdomain.com/
https://archive.org/details/prelinger
https://www.pond5.com/