Data Structure. - Marci Sperber (Encyclopedia of GIS, 2008)

Quadtree and Octree. - Marci Sperber (Encyclopedia of GIS, 2008)

Data Structure. - Marci Sperber (Encyclopedia of GIS, 2017)

Quadtree and Octree. - Marci Sperber (Encyclopedia of GIS, 2017)