 Complete the following phrase:  Leyb Moiseyevich Kvitko ,  October 15, 1890  August 12, 1952 was a prominent Yiddish poet, an author of well-known childrens poems and a member of the Jewish Anti-Fascist Committee JAC. He was one of the editors of Eynikayt the JACs newspaper and of the Heymland, a literary magazine. He was executed in Moscow on August 12, 1952 together with twelve other members of the JAC, a massacre known as the 