Band are accused of copying the guitar riff for their classic track
Band are expected to attend Los Angeles trial
Listen to 'The Lemon Song'
Court case argues that former tourmate should be given a writing credit on the song
Zeppelin guitarist raves about Donegan's 'Rock Island Line' in new book
The guitarist claims the frontman made the offer in 1975
Bonham isn't sure such a performance would be public, however
'Presence,' 'In Through the Out Door' and 'Coda' have all been remastered and re-released
Guitarist says the band can't agree on the right reasons to reunite