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: "who claimed to have discovered an iron law of oligarchy?" whose answer is Robert Michels.
Each document should contain about 30 words, and these documents should contain useful information.

Query: "iron law of oligarchy" origin
Useful Output:

Doc 1: What is the Iron Law of Oligarchy?  Robert Michels (1876-1924) wrote a book in 1911, The Iron Law of Oligarchy. According to Michels, if a democratic
Doc 2: He called this “the Iron Law of Oligarchy.” Robert Michels, from Wikipedia. What accounts for this iron law? First, as an organization grows
Doc 3: More than 100 years ago, Robert Michels laid out his theory of the 'iron law of oligarchy'. The main, and crucial, point Michels made is
Doc 4: In 1911, sociologist Robert Michels, set forth his Iron law of oligarchy, describing the tendency of all organizations, regardless of their
Doc 5: If there is an iron law of oligarchy, after all, then the scientific opponents of democracy -- though I wish to note here that I don't think