1. Bieberbach, L. (1911) Über die Bewegungsgruppen der Euklidischen Räume. Math. Ann., 70, 297–336; 72 (1912), 400–412.
2. Delone (Delaunay), B. N. (1934) Sur la sphére vide (French) Bulletin’ AN SSSR, mat., est., 793–800.
3. Berger, R. (1966) The undecidability of the domino problem. Memoirs of the AMS, 66, 1–66.
4. Robinson, R. M. (1967) Seven polygons which admit only nonperiodic tilings of the plane. Notices Amer. Math. Soc., 14 835
5. (1971) Undecidability and nonperiodicity of tilings of the plane. Inventiones Math., 12 177-209.