This week's Friday Brain-teaser from xrefer tests your knowledge of middle names. Answers here:

1. What was the middle name of Robert Stevenson, author of Treasure Island, whose initials were R. L. S. ?
2. Is Nelson Mandela's middle name Frederick or Rolihlahla?
3. What was the middle name of the 19th-century British writer Thackeray, author of Vanity Fair?
4. What is the middle name of tennis star John McEnroe: Patrick, Michael or Raymond?
5. What was the middle name of the 35th US president, J. F. Kennedy?
6. In the name of the English author, D. H. Lawrence, what does the "H" stand for?
7. What is the middle name of Canadian singer k. d. lang: Dawn, Deirdre or Dionne?
8. What is the middle name of US president George W. Bush?
9. What is the middle name of American actress Julia Roberts: Mary, Fiona, or Ann?
10. What is the middle name of US film star Sylvester Stallone: John, Igor or Enzio?