Campbell's most famous work is Dear Zoo, first published in 1982. Campbell says that he was inspired by seeing other early lift-the-flap books, such as Spot the Dog, and wanted to incorporate the flaps into a story so that they made sense. He then thought of explorers sending animals to zoos years ago in crates, and hit upon the structure of each flap being a container holding a different animal.
![](https://i.ytimg.com/vi/dCOpvD-27wY/mqdefault.jpg)