The Klein Bottle Book
A book about the Klein bottle that you can judge by its cover, since outside and inside are the same.
Use this cartoon
Free for classrooms, worksheets, slides and other non-commercial use under CC BY-NC 4.0, with credit to Ben Orlin.
Cartoon by Ben Orlin, Math with Bad Drawings. https://cartoons.mathwithbaddrawings.com/2016-01-27-the-klein-bottle-book/ (CC BY-NC 4.0)Transcript
[Book cover] "The Klein Bottle Book: The Outside Is the Inside. Welcome to the book you can judge by its cover."