1. Five balltree construction algorithms;Omohundro,1989
2. Ray tracing using hierarchies of slab cut balls;Källberg,2010
3. Hierarchical discrete medial axis for sphere-tree construction;Broutta,2009
4. Optimized 2D ball trees;Retondaro,2021
5. Implementing a zooming user interface: experience building Pad++;Bederson;Softw Pract Exp,1998