Published in Nautilus, in 1994, in volume 107, pages 81-93
Published in Nautilus, in 1994, in volume 107, pages 94-96
Published in Nautilus, in 1994, in volume 107, pages 104-106
Published in Nautilus, in 1994, in volume 107, issue 3, pages 97-103
Published in Nautilus, in 1994, in volume 108, issue 1, pages 1-8