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: "when was the post it note first sold?" whose answer is 1977.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when were post-it notes first sold
Useful Output:

Doc 1: The very first Post-It hit the store shelves in 1980. 4. A Post-It  Today over £1 Billion worth of Post-It notes are sold each year.
Doc 2: The two teamed up to create what we know now as Post-it Notes in 1974, though the product didn't take off for another few years. It was first
Doc 3: The Post-it Note Was Invented By Accident (1968). When Spencer Silver, an employee researcher at 3M, was trying to create a stronger adhesive
Doc 4: Fry and Silver came up with what 3M originally called the Press 'n' Peel memo pad in 1974, but it wasn't brought to the market until 1977 and
Doc 5: Their invention is thanks to a Dr. Spencer Silver, a 3M scientist who in 1968 was busy researching adhesives in an attempt to find a super