Who wrote the book On Wallaby?

There is no book called "On Wallaby." It's possible you're misremembering the title or author.

Could you please provide more information? For example:

* What is the book about? (e.g., a children's book, a scientific study, a novel about a wallaby)

* Do you remember any other details about the book? (e.g., the cover, the setting, the main characters)

With more information, I can help you find the book you're looking for.