https://docs.google.com/document/d/e/2PACX-1vQslx8ACVDEVz5OJ5owkJxiicINVCg5hqrw0PcJBQdsWKhlV-I4MgYPLqNgnDJ_oLqFEm5JbDXBBb3g/pub
An article covering the two rulebooks from Compass Games Spring Prelude and Kharkov Battles,  click the link to read: