| Clue | Source | Date |
|---|---|---|
| They prevent accidental scribbles | New York Times | 24 Mar 2024 |
| Ballpoint covers | The Washington Post | 12 May 2021 |
| Ballpoint covers | LA Times Daily | 12 May 2021 |
| Stoppers of ink stains | Newsday | 28 Jan 2021 |
| Things removed before signing | New York Times | 15 Aug 2015 |
| Things removed before signing |