The owners of Cosmopolitan magazine say its long-time editor, Helen Gurley Brown, has died in New York at the age of 90. Helen Gurley Brown became famous in 1962 after writing the bestseller Sex and the Single Girl – a book of advice and anecdotes on why being single shouldn't mean being sexless. Widely credited with helping to encourage the female sexual revolution, she was hired by Hearst which owns Cosmopolitan in 1965 to improve the magazine's fortunes. _______________________________________________________.