Sibelius continued his studies in Berlin (from 1889 to 1890) with Albert Becker, and in Vienna (from 1890 to 1891) with Robert Fuchs and Hungarian-Jewish Karl Goldmark. In Berlin, he had the opportunity to widen his musical experience by going to a variety of concerts and operas, including the premiere of Richard Strauss's "Don Juan". He also heard the Finnish composer Robert Kajanus conducting the Berlin Philharmonic in a program that included his symphonic poem "Aino", a patriotic piece that may have triggered Sibelius's later interest in using the epic poem "Kalevala" as a basis for his own compositions. While in Vienna, he became particularly interested in the music of Anton Bruckner whom, for a time, he regarded as "the greatest living composer", although he continued to show interest in the established works of Beethoven and Wagner. He enjoyed his year in Vienna, frequently partying and gambling with his new friends. It was also in Vienna that he turned to orchestral composition, working on an Overture in E major and a "Scène de Ballet". While embarking on "Kullervo", an orchestral work inspired by the "Kalevala", he fell ill but was restored to good health after gallstone- excision surgery. Shortly after returning to Helsinki, Sibelius thoroughly enjoyed conducting his Overture and the "Scène de Ballet" at a popular concert. He was also able to continue working on "Kullervo", now that he was increasingly developing an interest in all things Finnish. Premiered in Helsinki on 28 April 1892, the work was an enormous success.