Great movie. Even though it was supposed to be based on the novel "The Short Timers" by Gustav Hasford, the screenplay was cowritten by Michael Herr, and he incorporated a lot of dialogue and stories from his great book "Dispatches." I\'m pretty sure that\'s where the story about shooting women and children from the door of the Huey came from. Also the dialog about the US soldier offering ARVN rifles for sale. "Never been fired, and only dropped once."
If you want to read some good books on the Vietnam war, I recommend:
"The Things They Carried" - Tim O\'Brien
"Going After Cacciato" - Tim O\'Brien
"If I Die in a Combat Zone" - Tim O\'Brien
"The Thirteenth Valley" - John Del Vecchio
"Close Quarters" - Larry Heinemann
"Dear America: Letters Home from Vietnam" - Bernard Edelman
"A Rumor of War" - Philip Caputo