1. S. Beatty, Problem 3173, Am. Math. Monthly 33 (1926) 159; solutions in 34, 159 (1927).
2. R. Berger, The Undecidability of the Domino Problem, Mem. Amer. Math. Soc. 66 (1966)
3. K. Culik II, An aperiodic set of 13 Wang tiles, Discrete Mathematics 160, 245–251 (1996).
4. K. Culik II and J. Kari, An aperiodic set of Wang cubes, Journal of Universal Computer Science 1, 675–686 (1995).
5. B. Grünbaum and G.C. Shephard, Tilings and Patterns, W.H.Freeman and Company, New York (1987).