When I created the GIS file with the contours of the former borders of the Third Bulgarian Kingdom, it was more of a shadow and an interesting continuation of the GIS file of modern boundaries. Just a hint of historical projects and reference maps.
That is why, not until the end of October 2017, I began to fill the outline of these borders, with a date reliant on their historical vision. And next on this project is a geojson file with 1600 populated places with their names from 1912-1930 with their spelling specific to this time. I hope to have time to work on the project in the future and create similar files for geographic names, road network, etc.