I want to release a program that uses some public domain code (or a permissive license) from netlib.org under the LGPL license. Since the licenses (or lack of it) are compatible, there should be no problem distributing the bundle in source or binary form, right?
In practice, I should add a copyright and license header to every source file. For those files I took from netlib.org, I cannot add a copyright (not on my name, for sure, and sometimes I don't know the original author or I can't add a copyright to a file that has none), but is it OK to add the license header (basically, "This file is part of Foo. Foo can be distributed under the terms of the LGPL")? I find that at least morally I should add a further notice saying "This file comes from netlib.org and is public domain/whatever".
If the answer is that I shouldn't add the header in such a file, would it change if I merge two files, one written by me, one public domain, and add the header to that?