(CNN) -- Kitty Kelley, biographer of the rich and famous, is getting ready to release an unauthorized biography on talk show queen Oprah Winfrey.



The 544-page book, "Oprah: A Biography," will be released on April 13, with a first printing of 500,000 copies, according to the Crown Publishing Group.



"We are excited to be publishing the first comprehensive biography of one of the most influential, powerful and admired public figures of our time, by the most widely read biographer of our era," said Tina Constable, a vice president with Crown.



The author spent three years researching for the book and conducted 850 interviews, Crown said.



Kelley's previous books have chronicled the Bush family political dynasty, the British royal family, Frank Sinatra, Elizabeth Taylor, Jacqueline Kennedy Onassis and Nancy Reagan.



Winfrey's Harpo Productions had little to say about the book.



"Oprah hasn't participated in or read Kitty Kelley's book, so she is unable to comment," said Winfrey spokeswoman Lisa Halliday.
When will the book be released? Who else has the author written biographies on? What is the name of Oprah Winfrey's tell- all? its authorized or not? Who will write the biography? What other biographies has Kelley written?
April 13, the Bush family political dynasty, the British royal family, Frank Sinatra, Elizabeth Taylor, Jacqueline Kennedy Onassis and Nancy Reagan. "Oprah: A Biography," unauthorized Kelley, the Bush family political dynasty, the British royal family, Frank Sinatra, Elizabeth Taylor, Jacqueline Kennedy Onassis and Nancy Reagan.
question: When will the book be released?, answer: April 13, | question: Who else has the author written biographies on?, answer: the Bush family political dynasty, the British royal family, Frank Sinatra, Elizabeth Taylor, Jacqueline Kennedy Onassis and Nancy Reagan. | question: What is the name of Oprah Winfrey's tell- all?, answer: "Oprah: A Biography," | question: its authorized or not?, answer: unauthorized | question: Who will write the biography?, answer: Kelley, | question: What other biographies has Kelley written?, answer: the Bush family political dynasty, the British royal family, Frank Sinatra, Elizabeth Taylor, Jacqueline Kennedy Onassis and Nancy Reagan.