- http://dbs.mathematik.uni-marburg.de/publications/myPapers/1990/BKSS90.pdf
- http://www-db.deis.unibo.it/courses/SI-LS/papers/Gut84.pdf
- http://www.win.tue.nl/~hermanh/stack/dagstuhl08-talk.pdf
- http://courses.cs.washington.edu/courses/cse373/02au/lectures/lecture22l.pdf
- http://wikipedia.com
- http://cedric.fleu.free.fr/media/rapportCTR_cfleury.pdf
- http://www.irisa.fr/prive/kadi/DIIC/SDI-2-annee/Expose_KdTree.pdf
- http://technet.microsoft.com/en-us/library/bb964712(v=sql.105).aspx
- http://workshops.boundlessgeo.com/postgis-intro/indexing.html
- https://github.com/mourner/rbush
- http://www.gaia-gis.it/gaia-sins/spatialite-cookbook/html/rtree.html