When addressing adolescent girls and unmarried ladies under the age of 30, use "Miss." When you are unsure of a woman's marital status, if she is single and above 30, or if she chooses to be addressed with a marital-status neutral title, use "Ms." When addressing a married lady, use "Mrs." or "Ms." depending on how she prefers to be addressed. MS refers to Mary Sue. This name is given as a joke or parody name, usually used in reference to a female character who is very good-looking but lacks any discernible personality traits other than being attractive. The term Ms. appears in print for the first time in an issue of The New Yorker magazine on February 20, 1975. It was written by John Coleman, who was later appointed chief creative officer at MTV Networks. The article was titled "Mary Sue and John Brown," and it described these two names as "the last words in naming your daughter". In 1998, the term made its way into popular culture through the book And Then There Were None, which was written by Agatha Christie and featured ten apparently unrelated sentences that were actually links to each other. Each sentence began with the word "Ms.," which acted as a link between all ten stories. Christie introduced the term into the book when discussing the names people had chosen for their daughters: "Most often they choose some variant of Mary or Marilyn.