Published in Nautilus, in 1989, in volume 103, pages 1-12

Published in Nautilus, in 1989, in volume 103, pages 13-19

Published in Nautilus, in 1989, in volume 103, pages 43-69

Published in Nautilus, in 1989, in volume 103, pages 70-72

Published in Nautilus, in 1989, in volume 103, pages 92-95