Where do I get my information? I lived through it. I'm 68. Perhaps you're younger and don't remember the Vietnam war.
Here's a bit of my biography that might explain something to you. When I was 17, about to turn 18, my parents pushed me into joining the Navy to avoid being drafted into the Army, thus to keep me a step or so back from any war. Since I was still 17 when I joined, I was in for what was called the Minority Enlistment: Join before you're 18, you get out the day before you turn 21. Those of us in for the minority enlistment were called, in the Navy, "kiddie cruisers." I joined in 1961 and was released from active duty in 1964. In addition to getting out before I turned 21, I got an earlier out to start college. I would have gotten out in mid October, but actually got out in early September of 1964.
I was raised in the 'burbs and was rather insulated from the outside world. Thus, my political values were somewhat moderate to conservative. During my last year of enlistment I discovered the works of Ayn Rand and became infatuated with her philosophy of objectivism. It really did appeal to a 20 year-old with limited life experience. In 1964 I registered as a Republican and enthusiastically voted for Barry Goldwater. Thus, when the Vietnam war started, I was an avid supporter of the war.
My support for the Vietnam war steadily eroded when government after government in South Vietnam fell. Each one was touted by the Johnson administration to be the one that would bring political stability to South Vietnam. None of them did. Further, year after year of American involvement in the war failed to make any gains. No territory was taken from the Viet Cong, and there was no conversion of the countryside into supporting our side in the struggle.
I began the war as an Ayn Rand enthusiast and a Goldwater Republican. By the end of the war, I was on the political left. Reality and my initial political ideology clashed. Eventually, reality won.
Let me end with an anecdote that indicates the duplicity of the American government toward its people concerning why and when we were drawn into that conflict. I was a hospital corpsman in the Navy. One of the hazards of being a Navy corpsman is that, upon graduation from Hospital Corps school, you might get sent to the Fleet Marine Force; i.e. you had joined the Navy, only to end up wearing Marine uniform, undergoing infantry training and being in combat with the Marines. Generally, only one or two guys from each company would be taken into the Fleet Marine Force. Suddenly, as our company was about to graduate in 1962, they started taking whole companies for the Fleet Marines (They leap-frogged our company, and I was spared that danger). The rationale given for this was that they were building up WestPac, i.e. the west Pacific Fleet. Since we were all naive 18 year-olds, t didn't occur to us to ask why they were building up WestPac. Of course, they were building it up to get ready for the Vietnam war. Thus, the assertion that we only went into Vietnam reluctantly in 1964 in response to North Vietnamese PT boats attacking our Navy ships is bogus.
Frankly, I think my living through the years of the Vietnam war trumps any book you can throw at me.