Hello

I want to create sfx based on 50s/60s radio recordings. It can be songs or radio programs, that I could later edit sample in priopriate way.

Do you know any sites with such a audio material? Preferably in public domain or CC0 

Regards
Crane

You have to be really careful when it comes to music because 50's/60's songs are "young" enough to still have copyright applied. Even songs that are older could still be under copyright if the estate chooses to extend out the copyright. Dialog could be something completely different. Having said that, sometimes older documentary style films can be copyright free. Sometimes. You really have to do your research. 

You could also just look up radio sound effects from royalty free libraries. Sites like https://www.soundrangers.com/ or https://www.sounddogs.com/ could help. Something like this *might* work too but you should still do your research first: https://archive.org/search.php?query=radio 

Hope that helps!

Nate