https://www.arcgis.com/apps/Cascade/index.html

https://github.com/ljvmiranda921/seagull

https://neo4j.com/blog/going-underground-graphing-pathfinding-london-tube-lines/

https://twitter.com/hardsci/status/1125828370355277824

http://groupexplorer.sourceforge.net/index.html

https://obsolescence.wixsite.com/obsolescence/pidp-11

https://www.youtube.com/user/JimSterling