Hello,
How can I find out if a song is still protected by copyright ?

I DONT want to start a discussion on the pro's and con's of copyright, that's a whole different subject.

I always thought if the writer of the song is at least 70 years dead, the songs are free to use but f.i. Robert Johnson songs are still protected despite the fact that he is dead since 1938.

So is there a website where you can check if there is still (international ?) copyright on a song ?

thanks

Moos