add a link to a book about r-trees
add a link to a book about r-trees

mourner/rbush,josl/rbush,mourner/rbush,MazeMap/rbush,korczis/rbush,korczis/rbush,landonb/rbush,opentable/rbush,opentable/rbush,MazeMap/rbush,landonb/rbush,josl/rbush