Publisher Bloomsbury is being sued by the estate of English children's writer Adrian Jacobs over claims that JK Rowling copied his work in one of her Harry Potter books.It believes Rowling used "substantial parts" of Jacobs' "The Adventures of Willy the Wizard-No 1 Livid Land" in "Harry Potter and the Goblet of Fire".The estate, which issued proceedings in the High Court of England today, is seeking an injunction to prevent further sales of the book and either damages or a share in the profits made by Bloomsbury.It also alleges that Jacobs asked literary agent, Christopher Little, to help get Willy the Wizard published. Little later became Rowling's literary agent.Jacobs became bankrupt following a stock market crash, dying penniless in 1997, a decade after his book was published.