GNU recommend make AUTHORS file for list of authors and contributos of a program. But how many "levels" of authors and contributors should contain the file? E.g. I write a program foo, that actively use some library. Should I include authors of the library in the AUTHORS? It seems to yes, because total code of foo contain code from library. But if yes, I should include also authors of all others libraries, including standard libraries of compiler, authors of the compiler and other tools for producing final executable code, authors of OS... When I should stop?