>>87
See, for example:
1. the Preamble of GPLv3 itself
https://www.gnu.org/licenses/gpl-3.0.en.html
2. A Quick Guide to GPLv3
https://www.gnu.org/licenses/quick-guide-gplv3.html
3. Why Upgrade to GPLv3
https://www.gnu.org/licenses/rms-why-gplv3.html