Scott Adams (2007). “Stick to Drawing Comics, Monkey Brain!: Cartoonist Explains Cloning, Blouse Monsters, Voting Machines, Romance, Monkey G ods, How to Avoid Being Mistaken for a Rodent, and More”, p.451, Penguin
"Über das Unendliche" ["On the Infinite"] (1925) address to der Westfälischen Mathematischen Gesellschaft in honour to the memory of Karl Weierstrass, as quoted in "Number The Language of Science" by Tobias Dantzig, 1930.