Joan Baez: Love Is Just A Four-Letter Word
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I'm not sure if this counts as a cover. It was written by Bob Dylan but never recorded by him. Joan's is the first version, but you can hear Bob's style in the song's structure and lyrics. In any event, it's a fabulous song and Joan Baez's rendition is quite beautiful. Listen a few times and you'll be hooked.
Here's an interesting story about the song:
"In the 2005 PBS American Masters documentary on Dylan, No Direction Home, Baez told an amusing story of how she was with Dylan, when he first heard her recording of 'Love is Just a Four-Letter Word' on the radio. He commented on it, 'Hey, that's a great song!,' apparently having forgotten that it was he who'd written it."
(Source: Wikipedia).