Introduction to geometry. At least in my digital composition of a book repeated several times to make an implied X shape. I haven’t read this one. It’s cover and text are printed on cheap stock that’s probably not acid-free which accounts for the pages turning dry to the touch and brown-like in color. I’m afraid to open it up for a read because the binding is shot and pieces seem to flake off in my fingers. Despite this, no harm came to this kitschy cover while drawing it. (Unknown illustrator)