| Clue | Source | Date |
|---|---|---|
| Units for measuring bacteria and dust | New York Times | 16 Aug 2025 |
| Millionth-of-a-meter measures | The Washington Post | 12 Feb 2021 |
| Millionth-of-a-meter measures | LA Times Daily | 12 Feb 2021 |
| Tiny lengths | New York Times | 07 Nov 2015 |
| Tiny lengths | ||
| Meter millionths | ||
| Small measures |