| 1 | The lecture was given under the auspices of the Academy of Sciences. | |
| 2 | The work appears in the Proceedings of the National Academy of Sciences. | |
| 3 | The research is published in Proceedings of the National Academy of Sciences. | |
| 4 | The findings appear in the Proceedings of the National Academy of Sciences. | |
| 5 | The results appear this week in the journal Proceedings of the National Academy of Sciences. |