I've been a fan of Bob's since his first recordings but couldn't help but notice that he credited Martin Carthy's singing of Lord Franklin (trad) for the tune to Bob Dylan's Dream, yet years later didn't mention Nic Jones when he recorded what I and many others regarded as a direct copy of his version of Canadee-i-o. Regular readers of this forum will know all about Nic's circumstances.
Still if we are considering 'failure to acknowledge sources' I offer two words. The first is Led ...