"Mood Indigo" (1930) is a jazz composition and song, with music by Duke Ellington and Barney Bigard with lyrics by Irving Mills.

Disputed authorship - In a 1987 interview, Mitchell Parish claimed to have written the lyrics:

Prior to the rock era, which brought high-powered entertainment lawyers into the music industry, business was often conducted casually, sometimes on a handshake. Mr. Parish is somewhat rueful, though no longer bitter, over the fact that although he wrote the lyrics for Duke Ellington's "Mood Indigo," which was published in 1931, Irving Mills (Jack Mills's brother and publishing partner) took official credit.

List of 1930s jazz standards
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http://en.wikipedia.org/wiki/Mood_Indigo