Before revision:  Our proof\etal  is constructive and yields a linear-time algorithm for finding the points .
After revision:  However, both these proofs are non-constructive, at least in the sense that they do not seem to imply an efficient algorithm for finding the stabbing points, given such a set of disks D. Recently, Har-Peled\etal is constructive and yields a linear-time algorithm for finding the points .