Several of my friends have the idea that all sources should be recognised , wether for composed or traditional material and NOT just assume because you have heard someone sing a song it is 'Theirs' . I do NOT write , so use Albums and live performance to acquire new material . After I have workes out a song , if i think it sounds too much like the source , I put it away for a while , then go back to it and eventually get it sounding like MY treatment and NOT a steal of someone elses .