Who is Various Cartoon and storybook characters from Sophie's World and what is their importance?

Various cartoon and story book characters are deployed throughout the story to play with and harass Sophie and Alberto. These characters include Alice in Wonderland, Donald Duck, The Emperor with No Clothes, the Little Match Girl, Ebenezer Scrooge and others. Some of the characters also join Sophie and Alberto and the end of the book, when they join the invisible people.