| Clue | Source | Date |
|---|---|---|
| Incorporates gradually | Premier Sunday | 09 Jul 2023 |
| Gradually introduces middlemen in Spanish novel | Irish Times Crosaire | 28 Oct 2020 |
| Introduces slowly | New York Times | 23 Apr 2017 |
| Introduces slowly | ||
| Introduces gradually | ||
| Adds gradually | ||
| Introduces gradually | ||
| Gradually takes effect |