 The children's list was printed monthly until February 13, 2011, when it was changed to once an issue (weekly).In September 2007, the paperback fiction list was divided into "trade" and "mass-market" sections, in order to give more visibility to the trade paperbacks that were more often reviewed by the newspaper itself.In November 2010, "The New York Times" announced it would be tracking e-book best-seller lists in fiction and nonfiction starting in early 2011.