@article{GDZPPN002088959, title = {Undecidability and Nonperiodicity for Tilings of the Plane.}, journal = {Inventiones mathematicae}, volume = {14}, year = {1971}, pages = {177-209}, zbl = {0197.46801}, url = {http://dml.mathdoc.fr/item/GDZPPN002088959} }
Robinson, Raphael M. Undecidability and Nonperiodicity for Tilings of the Plane.. Inventiones mathematicae, Tome 14 (1971) pp. 177-209. http://gdmltest.u-ga.fr/item/GDZPPN002088959/