Good introduction to VIETNAM ERA terms and keywords. GRUNT is a good resource for running encounters involving unseen ambushers. I use it as a resource for creating ambushes (lots of ambush inspiration and good introduction to how a weaker force engages a more powerful force) and running gaming-as-war style rpgs. Gritty, dark style of play that reflects some of the horror of the period. Simple and effective mechanic for handling the stress of combat and horror of war.