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Every nontrivial file needs a license notice as well as the copyright notice. (Without a license notice giving permission to copy and change the file, the file is non-free.)
The package itself should contain a full copy of GPL (conventionally in a file named COPYING) and the GNU Free Documentation License (included within your documentation). If the package contains any files distributed under the Lesser GPL, it should contain a full copy of that as well (conventionally in a file named COPYING.LESSER).
If you have questions about license issues for your GNU package, please write licensing@gnu.org.