http://ngntfwmwovvku6eqi7dzzgzv2wzlvq2cqtqha7ccgzub2xnivsuxnuyd.onion/doc/license
There are many ways you could offer source, and different
solutions will be better for different programs; see section 13 for
the specific requirements. You should also get your employer (if you work as a programmer) or
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.