Good news for Potter fans. Come September and three new Harry Potter e-books will be available to readers. These include new stories about some of J K Rowling's characters from the Hogwarts school of witchcraft and wizardry. The e-books will be available on the website as well as through digital book sellers. The approximately 10,000-words long e-books are intended for tablets, cellphones and other mobile devices, and as a supplement to the original Harry Potter books, which have sold more than 450 million copies worldwide.