First of all, every math book—text or popular—contains a Lewis Carroll quote. It’s a rule.
Second, as noticed, there are two Alice books, Alice’s Adventures in Wonderland and Through the Looking Glass, though they are often published in one volume.
Thirdly, Carroll threw in all sorts of characters and references and parodies of things from all over the place (poems, nursery rhymes, etc.)—sorta like the Shrek movies. In addition to Humpty Dumpty, you’ll find the Knave of Hearts Who Stole the Tarts, Tweedle-dum and Tweedle-dee (Carroll didn’t invent the names but he made the characters his own), a parody of “Twinkle, Twinkle, Little Star,” and lots more that you may or may not recognize.
Fourthy, there is no fourthly. If I think of a fourthly later, I’ll come back and insert it.
Fifthly, the “accompanying sketch” is probably by English cartoonist John Tenniel, who drew the illustrations for the books. His pictures are irrevocably liked with the books and still appear in at least a majority of printed editions.
Sixthly, what the hell are you waiting for? Read the darn books already! If you have the right kind of sense of humor, they’re among the funniest things ever written. I particularly recommend Martin Gardner’s Annotated Alice, which explains many of the jokes and allusions.