Juhani Karhumäki Yury Lifshits Wojciech Rytter Tiling Periodicity. 237-248 2010 12 Discrete Mathematics & Theoretical Computer Science 2 http://www.dmtcs.org/dmtcs-ojs/index.php/dmtcs/article/view/1352 db/journals/dmtcs/dmtcs12.html#KarhumakiLR10