One thing I've discovered about the Vietnam War is that there is an amazing amount of information available. Further, many extensive archives of information can be accessed for free. The first stop for me was the U.S. Army Center of Military History (CMH). This site has extensive online resources including a huge number of Vietnam era publications. These range from interesting if I had three lifetimes to work with (Law in War Vietnam, 1964-1973) to more directly relevant titles like Seven Firefights in Vietnam and Mounted Combat in Vietnam. Many are written during the war or soon after it ended.
The information from the CMH is a great place to start. It's useful in it's own right and if you read between the lines you can get a sense of some ongoing controversies and struggles. For example, in the preface of Mounted Combat in Vietnam:
eight years of fighting over land on which tanks were once thought to be incapable
of moving, in weather that was supposed to prohibit armored operations, and
dealing with an elusive enemy against whom armored units were thought to be
at a considerable disadvantage, armored forces emerged as powerful, flexible,
and essential battle forces. In large measure they contributed to the success
of the free world forces, not only in close combat, but in pacification and
security operations as well."
No one serves the haters like a military writer.
One downside to the list of publications is that the selection seems haphazard. This is not the definitive site for research, but it's a good place to start.