In the early 20th century, impressionism was spreading across Slovenia, which soon produced composers Marij Kogoj and Slavko Osterc. Avant-garde classical music arose in Slovenia in the 1960s, largely due to the work of Uroš Krek, Dane Škerl, Primož Ramovš and Ivo Petrić, who also conducted the Slavko Osterc Ensemble. Jakob Jež, Darijan Božič, Lojze Lebič and Vinko Globokar have since composed enduring works, especially Globokar's ''L'Armonia'', an opera.