1. Continuous indexing of hierarchical subdivisions of the globe;Bartholdi;International Journal of Geographic Information Science,2000
2. Clarke, K.C., 2002. Criteria and measures for the comparison of global geocoding systems. In: Goodchild, M.F., Kimerling, A.J. (Eds.), Discrete Global Grids: A Web Book. University of California, Santa Barbara, http://www.ncgia.ucsb.edu/globalgrids-book.
3. A new world geographic reference system;Clarke;Cartographic and Geographic Information Systems,2002
4. Dutton, G.H., 1998. A Hierarchical Coordinate System for Geoprocessing and Cartography. Springer, Berlin, 230pp.
5. Global seismicity: 1900–1999;Engdahl,2002