"Humming Chorus" from "Madama Butterfly" by Giacomo Puccini, arranged for Flute sextet/choir by Francesco Leone (intermediate level).
Score and Parts: Flute 1, Flute 2, Flute 3, Flute 4, Flute 5, Flute 6 or Bass, optional part for G Alto Flute (6) included.  
Audio demo available on www.glissato.it - product code: EG1038