After "The Tale of Peter Rabbit" began to be sold, a great amount of merchandise copied its design and idea. Potter registered the patent for a Peter Rabbit doll on 28 December 1903. The next year, she designed a Peter Rabbit game. She made firm rules about making licensed merchandise such as dolls, books, tea sets, wallpapers, pencils and pens, cards, and other merchandise. Because the Peter Rabbit merchandise was so popular, Potter later said in 1917, "All rabbits "are" called Peter now". She did add for her American readers, though, "Peter or Brer Rabbit."