Hal Koerner's Field Guide to Ultrarunning

I listen to a podcast called Science of Ultra with Shawn Bearden so some of this is pretty familiar. Koerner goes through all the aspects of running ultras based on his experience of running and organizing races. It even includes training plans for various ultra distances(50km, 50 miles, etc) but doesn't tell you whether the distances in the plan are miles or kms? I guess it's probably American so imperial units like the nonsense monkeys they are.