http://u.qdnx.org/file/fsf-20180420T024919-bx45fg2.html
In this #LibrePlanet 2018 talk, "Browsing the free software commons," Stefano Zacchiroli @zacchiro delivers a primer on the Software Heritage project @SWHeritage, a vast public library of source code: https://u.fsf.org/2j2