When I worked on the Rise Again songbook, we included a Blues chapter that we're quite proud of. I got the job of researching the songs and finding out who wrote them and who owns the rights to them. I did the best I could, but it was a near-impossible job. Many of those songs that were recorded in the 1920s and 1930s, were recorded by four or five different artists the same year - with no songwriter attribution on any of them. I'm sure Led Zeppelin encountered the same problem, so I wouldn't be overly harsh in criticizing them. They revived good songs for a new generation that otherwise would never have heard anything like this.

And at the time, it was common knowledge that Led Zeppelin were singing a lot of old blues songs that they revived.

-Joe-

You can find our Blues Chapter here, if you're interested:

https://www.riseupandsing.org/songs/lists/chapters

(chapters are in alphabetical order)