 Other notable examples include Hindemith's and Ysaÿe's Sonatas for Solo Cello, Dutilleux's "Trois Strophes sur le Nom de Sacher", Berio's "Les Mots Sont Allés", Cassadó's Suite for Solo Cello, Ligeti's Solo Sonata, Carter's two "Figment"s and Xenakis' "Nomos Alpha" and "Kottos".The cello is a member of the traditional string quartet as well as string quintets, sextet or trios and other mixed ensembles.There are also pieces written for two, three, four or more cellos; this type of ensemble is also called a "cello choir" and its sound is familiar from the introduction to Rossini's William Tell Overture as well as Zaccharia's prayer scene in Verdi's Nabucco.