Autograph letter from the influential French composer, conductor and pedagogue, who signs for herself and her younger sister Lili Boulanger, sending music for a performance to the French soprano Marthe Chenal. 1 p.; n.p., n.d. [ca. 1910-1915]. Translated from the French: "Here is the music, dear friend - and all our joy! May you hear how sincere it is - Until soon - All our best wishes - Nadia and Lili Boulanger." On a grey-blue woven paper card, with very slight toning but overall in very fine condition. 5.25 x 3.75 inches (13.6 x 9.4 cm).