| Clue | Source | Date |
|---|---|---|
| Berlin's metro | Wall Street Journal | 14 Jun 2025 |
| Subway system in Berlin | Universal | 03 Jun 2025 |
| Berlin's subway | ||
| The Berlin subway system (1-4) | The Guardian Weekend | 26 Oct 2024 |
| German metro | ||
| German rapid transit system | New York Times | 14 Nov 2018 |
| German rapid transit system | ||
| Berlin subway | Newsday | 04 Jun 2016 |
| Vienna subway system | ||
| Berlin subway |