1. V. E. Alekseev, On the Skolem method of constructing Steiner triple systems (Russian), Mat Zametki, 2(1967) 145–156; MR 35 #5341. [x+y = z]
2. W. W. Rouse Ball fc H. S. M. Coxeter, Mathematical Recreations & Essays, 12th edition, Univ. of Toronto, 1974. [36-40 Nim & Wythoff’s Game; 115–116 squaring the square; 149–152 sphere packing; 189–192 latin squares; 193–221 magic squares; 222–242 map coloring; 271–311 combinatorial de-signs, an excellent survey written by J. J. Seidel]
3. Thøger Bang, On the sequence [nα], n = 1, 2,..., supplementary note to the previous paper by Th. Skolem, Math. Scand., 5(1957) 69–76; MR 19, 1159h. [Skolem problem]
4. S. Beatty, Problem 3173, Amer. Math. Monthly, 33(1926) 159; 34(1927) 159. [Beatty sequences]
5. Claude Beige, The Theory of Graphs and its Applications, Methuen, London, 1962, p. 38. [Isaacs’s Game]