He has written and illustrated over fifty children's books including George Shrinks, Santa Calls, Dinosaur Bob and his Adventures with the Family Lazardo, Rolie Polie Olie, The Leaf Men and the Brave Good Bugs and A Day with Wilbur Robinson.
Dia telah menulis dan mengilustrasikan lebih dari 50 buku anak-anak termasuk George Shrinks, Santa Calls, Dinosaur Bob and his Adventures with the Family Lazardo, Rolie Polie Olie, The Leaf Men and the Brave Good Bugs, dan A Day with Wilbur Robinson.