What album was it that the note from Ellie fell out of in Season 4, Episode #1 "The Same Deep Water As You"?

It is killing me. I know later in the episode they say it was a Led Zeppelin album, but they don't actually say what album it was. But there is a picture of it. :/ I would 愛 it if some one could figure it out for me. I 愛 Led Zeppelin :)