Letter to the Editor—Acknowledgment

It has been pointed out that our paper in Operations Research, 11, 889–900 (1963), is quite similar (even to the extent of notation in some cases) to a paper by W. Szwarc in Operations Research, 8, 782–788 (1960). To our embarrassment, we neglected to refer to this earlier paper. To say the least, it should have been given as a reference and, in fact, some of our results should be considered as rediscoveries of original contributions by Szwarc.