 Complete the following phrase:  Over the course of a long and prolific career, Ficher employed a variety of styles and techniques, including neoromanticism, neoclassicism, polytonality, twelve-tone technique, serialism, and free atonality, without ever restricting himself to a single methodology. His Jewish heritage is reflected especially in his early works, though the Second Symphony, written in 1933, also uses emotional and rhapsodic Hebrew thematic material, in reaction to news of the Nazi campaign against the Jews in Europe. This aspect also appears in some later works, especially the cantata Kadish, op. 112 1969, while the Russian tradition is plain in the two Anton Chekhov operas. French Impressionism and the influence of Paul Hindemith are present in the music from the 1920s and 30s, and as late as the slow movement of the Piano Sonata No. 1 of 1941, which is also reminiscent of Charles Koechlin and Darius Milhaud. Later, he turned to Argentine nationalism, stimulated by gauchesco literature in the overture Don Segundo Sombra 1954 after the novel by Ricardo Güiraldes, popular urban music in Tangos y milongas for piano 194859, rural folk music in Tres danzas populares, and historical themes in the Seventh Symphony, commemorating the 