| Clue | Source | Date |
|---|---|---|
| Equally scarce | Newsday | 15 Jun 2025 |
| Comparatively unique: 2 wds. | ||
| Equally hard to find | The Washington Post | 11 Jul 2019 |
| Equally hard to find | LA Times Daily | 11 Jul 2019 |
| Equally hard to find | ||
| Equally scarce | Universal | 08 Jan 2017 |
| Equally scarce | ||
| Comparable to hen's teeth | Wall Street Journal | 19 Mar 2016 |
| Equally unlikely | ||
| Equally unlikely | ||
| Comparable to hen's teeth | ||
| Equally unusual | ||
| Comparable to hen's teeth | ||
| Comparable to hen's teeth | ||
| Equally uncommon |