Authors, artists and musicians are due to gather at a library in San Francisco to protest against the banning of books in schools and libraries in the US. The event, part of the 27th annual Banned Books Week, has been organised by the American Library Association.
Since 2001 bans on 3,736 books and other materials have been requested. In recent years, And Tango Makes Three - based on a true story and centring on gay penguins in New York's Central Park Zoo - has had the most ban requests.