Read the chapter list. It presumes to cover everything up to and including the Winter War. I suspect that like most similarly ‘ambitious’ Ospreys there will be a lot of filler and scant detail, further reflected by a slim bibliography. Vis: Researching the Sino-Soviet War of 1929 has proved a bit tricky, so here have this potted history of Khalkin Gol rehashed from well known sources.
The similarly wide ranging Latin American Wars takes this approach. Cheeky buggers.