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: "Strahlen (Rays) for a percussionist (vibraphone and/or glockenspiel) and ten-channel sound recording is a composition by which German composer, widely acknowledged by critics as one of the most important ; but also controversial composers of the 20th and early 21st centuries?" whose answer is Karlheinz Stockhausen.
Each document should contain about 30 words, and these documents should contain useful information.

Query: German composer Strahlen rays vibraphone glockenspiel
Useful Output:

Doc 1: During his lifetime, Carl Loewe (1796-1869) built up a reputable career as a composer-singer, accompanying himself in public concerts, but his
Doc 2: Karlheinz Stockhausen (August 22, 1928 – December 5, 2007) was a German composer, widely acknowledged as one of the most important (Barrett 1988
Doc 3: Stockhausen Official website. Karlheinz Stockhausen's music, works and history of the famous 20th century composer.
Doc 4: Strahlen (Rays) for a percussionist (vibraphone and/or glockenspiel) and ten-channel sound recording is a composition by Karlheinz Stockhausen
Doc 5: Theodor Berger (1905–1992). Johann Nepomuk David (1895–1977). Hugo Distler (1908–1942), NSDAP membership Nr. 2.806.768, 1 May 1933. Otto Gerster (1897–1969).