| Clue | Source | Date |
|---|---|---|
| Watch them cover the inner surface in area that's clearly visible | ||
| Sight level | Thomas Joseph | 05 Feb 2025 |
| Face sketcher's horizontal reference | ||
| Face sketcher's horizontal reference | LA Times Daily | 03 Feb 2020 |
| Observation level | Newsday | 28 Sep 2019 |
| Middle of a field of vision | New York Times | 09 Jun 2018 |
| Middle of a field of vision | ||
| Horizontal view | Wall Street Journal | 24 Oct 2017 |
| Point of view? | LA Times Daily | 25 Feb 2017 |
| Face sketcher's aid | ||
| Face sketcher's aid | ||
| Horizontal view | ||
| A level. |