1. Amiri A, Harrison E, Samavati F. 2015a. Hexagonal connectivity maps for digital Earth. Int J Digital Earth, 8: 750–769
2. Amiri A, Samavati F, Peterson P. 2015b. Categorization and conversions for indexing methods of discrete global grid systems. ISPRS Int J Geo-Inform, 4: 320–336
3. Bai J J. 2011. Location coding and indexing aperture 4 hexagonal discrete global grid based on octahedron. J Remote Sens, 15: 1125–1137
4. Ben J, Tong X C, Yuan C P. 2011. Indexing schema of the aperture 4 hexagonal discrete global grid system (in Chinese). Acta Geodaet Cartogr, 40: 785–789
5. Ben J, Tong X C, Zhang Y S, Chen R G. 2007. Research on generating algorithm and software model of discrete global grid systems (in Chinese). Acta Geodaett Cartogr, 36: 187–191