Helfgott HA, Gessel IM. Tilings of Diamonds and Hexagons with Defects. Electron. J. Combin. [Internet]. 1999Feb.23 [cited 2026Mar.28];6(1):R16. Available from: https://www.combinatorics.org/ojs/index.php/eljc/article/view/v6i1r16