| Clue | Source | Date |
|---|---|---|
| Legislative delays | Universal | 29 May 2018 |
| Legislative delays | ||
| Intransigent senators' tactics | Universal | 11 Jun 2017 |
| Intransigent senators' tactics | ||
| Powerful parliamentary weapons in U. S. Senate. | ||
| Washington stratagems. | ||
| Bill-blocking oratory. |