You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "Oszkár Kálmán was the first lead of a one act opera by which composer?" whose answer is Béla Bartók.
Each document should contain about 30 words, and these documents should contain useful information.

Query: Oszkár Kálmán first lead one-act opera
Useful Output:

Doc 1: The main stage offerings this season were a heady mix of European operetta, Gilbert & Sullivan, and Broadway musicals, among them two choice
Doc 2: ENO has announced its 2018/19 season, comprising five new productions, four revivals and a gala performance at the London Coliseum.
Doc 3: He was Jewish and born in Kisszentpéter (in present day Romania) and in 1913 made his debut as Sarastro at the Royal Opera House in Budapest, where created the
Doc 4: The first one-act opera focuses on the bathing Gisela, who is  Kálmán (1882–1953). While the TOT has presented Kálmán's Countess
Doc 5: Bluebeard's Castle · Bartók · Oszkár Kálmán. Boaz, t, Ruth · Berkeley · Peter Pears. Bob  La damnation de Faust (first staged performance, Monte Carlo, 1893)