License?

[frohro]

Hi,
I note in the header file for nanasdr.h and a number of other source files, GPL, but there is no license here on github, and some files don't have the header for GPL? Could you clean this up a little. I'd like to use the code for my Electronics II class project, but feel a little uneasy, given some code has no GPL headers, and there doesn't seem to be a license file here on github.
https://help.github.com/en/articles/adding-a-license-to-a-repository
Thanks Eddy!
Rob