1. Erin Allen. https://blogs.loc.gov/loc/2016/09/lcm-making-of-the-modern-map (accessed: June 2020). Erin Allen. https://blogs.loc.gov/loc/2016/09/lcm-making-of-the-modern-map (accessed: June 2020).
2. Google. https://developers.google.com/maps/documentation/directions/start (accessed: June 2020). Google. https://developers.google.com/maps/documentation/directions/start (accessed: June 2020).
3. Google. https://developers.google.com/maps/documentation/javascript/tutorial (accessed: June 2020). Google. https://developers.google.com/maps/documentation/javascript/tutorial (accessed: June 2020).
4. GraphHopper. https://www.graphhopper.com/ (accessed: June 2020). GraphHopper. https://www.graphhopper.com/ (accessed: June 2020).
5. Microsoft. https://docs.microsoft.com/en-us/bingmaps/rest-services/routes (accessed: June 2020). Microsoft. https://docs.microsoft.com/en-us/bingmaps/rest-services/routes (accessed: June 2020).