In 1941 there was a strike against the American Society of Composers, Authors and Publishers, of which Duke Ellington was a member. Because of the strike he could not air his songs on the radio. Instead, he used songs written by his son Mercer and pianist Billy Strayhorn. Strayhorn's compositions of this time include "Take the 'A' Train", "Chelsea Bridge" and "Day Dream", and Mercer wrote "Things Ain't What They Used to Be", "Blue Serge" and "Moon Mist".