void rectangleSelectionCallback(Vector3 spherePosition1, Vector3 spherePosition2, bool finishRectangleSelection)
 {
     if (finishRectangleSelection)
     {
         List <Country> selectedCountries = map.GetVisibleCountries(spherePosition1, spherePosition2);
         Debug.Log("Countries found: " + EntityListToString(selectedCountries));
         List <Province> selectedProvinces = map.GetVisibleProvinces(spherePosition1, spherePosition2);
         Debug.Log("Provinces found: " + EntityListToString(selectedProvinces));
         List <City> selectedCities = map.GetVisibleCities(spherePosition1, spherePosition2);
         Debug.Log("Cities found: " + CityListToString(selectedCities));
     }
 }