Proceedings of the National Academy of Sciences of the United States of America. 12/24/2002, Vol. 99 Issue 26, p16853. 6p. 24 Color Photographs, 5 Diagrams.
Proceedings of the National Academy of Sciences of the United States of America. 12/24/2002, Vol. 99 Issue 26, p16847. 6p. 32 Color Photographs, 2 Diagrams, 1 Graph.