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: "where is the beginning of the mississippi river located?" whose answer is Lake Itasca.
Each document should contain about 30 words, and these documents should contain useful information.

Query: source of the mississippi river
Useful Output:

Doc 1: The Source of the Mississippi River-- Lake Itasca.
Doc 2: Upon reaching Upper Red Cedar Lake, Cass, like Pike before him, identified it as the source of the Mississippi River. But Schoolcraft had his
Doc 3: The Upper Mississippi Basin, for example, extends from its point of origin at Lake Itasca to the confluence of the Ohio and Mississippi rivers
Doc 4: The Mississippi River is the second longest river in North America, flowing 2,350 miles from its source at Lake Itasca through the center of the
Doc 5: Where does the Mississippi River begin? The Headwaters of the Mississippi River are officially located at Lake Itasca, Minnesota.