Larry Weiner is this great musicologist in the International Folk Dance and specifically Bulgarian music movement.
He is sharing all these rare really awesome (“lost”) tracks, but the website is set up to share them one at a time.
But using the Terminal in OSX (it’s in utilities) I was able to employ wget to retrieve the whole collection:
wget -r -np -k http://www.bg-popfolk.com/MUZIKA%20OT%20PERIODA%201905-1950/