Which leading Soviet Armenian composer composed the ballet whose libretto was written by Konstantin Derzhavin?
Konstantin Derzhavin:  He wrote the libretto to Aram Khachaturian's ballet "Gayane". Aram Khachaturian: Aram Il'yich Khachaturian ( ; Russian: Ара́м Ильи́ч Хачатуря́н ; Armenian: Արամ Խաչատրյան , "Aram Xačatryan"; ] ; 6 June [O.S. 24 May] 1903 1 May 1978) was a Soviet Armenian composer and conductor. Aram Khachaturian:  He is considered one of the leading Soviet composers.
Aram Khachaturian