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 wrote the first book about king arthur?" whose answer is Historia Regum Britanniae.
Each document should contain about 30 words, and these documents should contain useful information.

Query: first book about King Arthur
Useful Output:

Doc 1: Two of the earliest accounts of King Arthur were by William of Malmesbury (b. c. 1090, d. c. 1142) and Geoffrey of Monmouth (d. 1154/55), Anglo-
Doc 2: Stories about King Arthur became popular before the 11th century. Geoffrey of Monmouth's Historia regum Britanniae, written between 1135 and
Doc 3: In the popular 12th-century book History of the Kings of Britain, Geoffrey of Monmouth wrote the first life story of Arthur, describing his
Doc 4: First published in 1485, Le Morte D'Arthur by Sir Thomas Malory is a compilation and interpretation of the legends of Arthur, Guinevere, Sir
Doc 5: The first major Arthurian epic of the new millennium, The Bright Sword is steeped in tradition, complete with duels and quests, battles and