According to the ''Harvard Dictionary of Music'', "Argentina has one of the richest art music traditions and perhaps the most active contemporary musical life" in South America. Buenos Aires boasts of several professional orchestras, including the Argentine National Symphony Orchestra, the Ensamble Musical de Buenos Aires and the Camerata Bariloche; as well as various conservatories that offer professional music education, like the Conservatorio Nacional Superior de Música. As a result of the growth and commercial prosperity of the city in the late 18th century, theater became a vital force in Argentine musical life, offering Italian and French operas and Spanish zarzuelas. Italian music was very influential during the 19th century and the early 20th century, in part because of immigration, but operas and salon music were also composed by Argentines, including Francisco Hargreaves and Juan Gutiérrez. A nationalist trend that drew from Argentine traditions, literature and folk music was an important force during the 19th century, including composers Alberto Williams, Julián Aguirre, Arturo Berutti and Felipe Boero. In the 1930s, composers such as Juan Carlos Paz and Alberto Ginastera "began to espouse a cosmopolitan and modernist style, influenced by twelve-tone techniques and serialism"; while avant-garde music thrived by the 1960s, with the Rockefeller Foundation financing the Centro Interamericano de Altos Estudios Musicales, which brought internationally famous composers to work and teach in Buenos Aires, also establishing an electronic music studio.