Proceedings of the California Academy of Sciences 57: 1003-1010.

Proceedings of the National Academy of Sciences 95:14576- 14583.

Proceedings of the California Academy of Sciences 54: 393-406.

Proceedings of the National Academy of Sciences, 100: 9383-9387.

Proceedings of the National Academy of Sciences, 99: 12917-12922.

Proceedings of the National Academy of Sciences 97: 12144-12148.

Proceedings of the National Academy of Sciences 2: 672-675.

Proceedings of the National Academy of Sciences, 28 Mar. 2005.

Proceedings of the National Academy of Sciences 95: 853-860.

Proceedings of the National Academy of Sciences on line.