Begin MainProgram

    results = a new SET   (a kd-tree)
    search(space,root,results)
    return results
endMainProgram

Subroutine search(space,node,results)
    if (space contains node.region) then
        add node.point to the results
        for each descendant of node
            add d.point to results
        return
    if (space contains node.point) then
        add node.point to results
    if (space extends below node.coordinate) then
        search(space,node.below,results)
    if (space extends above node.coordinate) then
        search(space,node.above,results)
endsubroutine