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: "Boris Peter Bransby Williams is best known for his extensive work with a band formed in which year ?" whose answer is 1976.
Each document should contain about 30 words, and these documents should contain useful information.

Query: formation year Iron Butterfly
Useful Output:

Doc 1: All the sets on East 1968 end with the instrumental "Iron Butterfly Theme," which is clearly an example of "heavy" rock done years before Black
Doc 2: The track was recorded on May 27, 1968, at Ultrasonic Studios in Hempstead, Long Island, New York. The story goes that the recording that is
Doc 3: The band was formed in 1966 in San Diego, and they released their aforementioned debut album, 'Heavy', in 1968, after signing a deal with an
Doc 4: Legendary psychedelic rock band founded in 1966 well known for their mega hit 'In-A-Gadda-Da-Vida'. “Our music is more of a metaphysical statement.”
Doc 5: Born in Nebraska, Ingle was raised in San Diego where he formed Iron Butterfly in 1966 and signed to Atlantic Records, who released their debut