Find data source (or what is it) for TravelDistance function?

Questions
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1

Just a quick one. I’ve been using the TravelDistance function for some analysis. I want to cite the data source used by Mathematica (assuming there is an external information source), but can’t find any reference to that information.

Does anyone know a) how to find that information, or b) what the source is?

2

We are using GraphHopper deployment as internal engine, and it uses data dump from OpenStreetMap.

3

Thanks. A great help.

Just quickly, is this type of information in the documentation anywhere?

4

I couldn’t find it either, but I thought it was documented, anyway I will see where should it be added.