Originally posted by: davestar
I assume that most of Page's plagarism is common knowledge, but then again there's a ton of blind Zeppelin worship floating around these forums. For the uninitiated:
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Babe I'm Gonna Leave You" - A folk song by Anne Bredon, this was originally credited as "traditional, arranged by Jimmy Page," then "words and music by Jimmy Page," and then, following legal action, "Bredon/Page/Plant."
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Black Mountain Side" - uncredited version of a traditional folk tune previously recorded by Bert Jansch.
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Bring It On Home" - the first section is an uncredited cover of the Willie Dixon tune.
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Communication Breakdown" - apparently derived from Eddie Cochran's "Nervous Breakdown."
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Custard Pie" - uncredited cover of Bukka White's "Shake 'Em On Down," with lyrics from Sleepy John Estes's "Drop Down Daddy."
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Dazed And Confused" - uncredited cover of the Jake Holmes song (see The Above Ground Sound Of Jake Holmes).
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Hats Off To (Roy) Harper" - uncredited version of Bukka White's "Shake 'Em On Down."
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How Many More Times" - Part one is an uncredited cover of the Howlin' Wolf song (available on numerous compilations). Part two is an uncredited cover of Albert King's "The Hunter."
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In My Time Of Dying" - uncredited cover of the traditional song (as heard on Bob Dylan's debut).
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The Lemon Song" - uncredited cover of Howlin' Wolf's "Killing Floor" - Wolf's publisher sued Zeppelin in the early 70s and settled out of court.
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Moby Dick" - written and first recorded by Sleepy John Estes under the title "The Girl I Love," and later covered by Bobby Parker.
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Nobody's Fault But Mine" - uncredited cover of the Blind Willie Johnson blues.
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Since I've Been Lovin' You" - lyrics are the same as Moby Grape's "Never," though the music isn't similar.
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Stairway To Heaven" - the main guitar line is apparently from "Taurus" by Spirit.
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White Summer" - uncredited cover of Davey Graham's "She Moved Through The Fair."
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Whole Lotta Love" - lyrics are from the Willie Dixon blues "You Need Love." 
An interesting read:
Jimmy Page's Dubious Recording Legacy