Published in Nautilus, in 1990, in volume 103, pages 124-130
Published in Nautilus, in 1990, in volume 103, pages 143-148
Published in Nautilus, in 1990, in volume 104, pages 1-3
Published in Nautilus, in 1990, in volume 104, pages 57-70
Published in Nautilus, in 1990, in volume 104, pages 77-86
Published in Nautilus, in 1990, in volume 104, pages 96-104
Published in Nautilus, in 1990, in volume 104, pages 105-107
Published in Nautilus, in 1990, in volume 104, pages 111-119
Published in Nautilus, in 1990, in volume 104, issue 4, pages 130-144