knowledge of royalty free music



I search some music, I already found good stuff with cheap license but I need very specific things not very easy to find on internet so maybe someone can help.

1/ Is there some 1920 - 1940 music with free license?
2/ do you know any site where i can get free or cheap license for 1920-40 music? I already search some but everything I found with "royalty free music 1920" are never free -.- its like 20€ the song....

3/ i found this but I total nothing understood the "About" page (Im not English). Because its wrotte public domain, but I fear bad surprise


What is the Open Music Archive?

The Open Music Archive aims to gather together information about and recordings of public domain music. This is music whose copyright has expired. This music can be used by anyone for any purpose.
I would say you are good.