These are all documented, I like zep but they ripped off a ton of music, here are the songs side by side, you’ll be shocked !!
Part 1
http://www.youtube.com/watch?v=JyvLsutfI5M
Part 2
http://www.youtube.com/watch?v=zThdTAWQFAQ
Honestly, they took probably 50% of their songs from other people without giving them credit, give those a listen, you’ll be totally suprised man
Oh, and Part 3, even Stairway to heaven was ripped off
http://www.youtube.com/watch?v=K5uMQDlKn8g
The other Led Zep ripoffs pale in comparison to Jake Holmes’ “Dazed & Confused”. Holmes should have been after them ages ago.