NN (Wolka) was formerly part of the German Empire. In the German Empire, the place was called NN.
The place is now called Wólka (Mława-Wólka) and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| NN (Wolka) | Russian Empire | Mlava | 1914 |
| Wólka Nowa | Poland | Mława | 1919 |
| Wólka Stara | Poland | Mława | 1919 |
| NN | German Empire | Mielau | 1939 |
| Wólka Nowa (Mława-Wólka Nowa) | Poland | Mława | 1945 |
| Wólka Stara (Mława-Wólka Stara) | Poland | Mława | 1945 |
| Wólka (Mława-Wólka) | Poland | Ciechanów | 1992 |