The Book in the Book in the Book

Thomas is on vacation with his parents when his parents decide to nap. Thomas takes a walk and finds a book. What is the story inside? In the book, Thomas is on vacation with his parents when his parents decide to nap. Thomas takes a walk and finds a book. And so on...

Just the sort of quirky book I love. As a child I would have read this one over and over. And probably made my own version. And maybe I will do this now.