This job offers some good information for this question:
3) While most Americans persist in the belief that the United States lost the war in Vietnam, there is considerable evidence to suggest that the U.S. military and intelligence services, operating under the political and diplomatic constraints imposed on them by politicians, the public, Cold War circumstances, and international public opinion were not, and never were, defeated on the battlefield. write an essay either supporting or opposing this idea. Did the U.S. really lose the war? Discuss the strategies and tactics used during the "big unit" war and the later "one approach" war. What evidence is there to support the suggestion that the U.S. actually won the ground war? In what ways was the U.S. military and intelligence services successful and in what ways did they fail?© BrainMass Inc. brainmass.com March 4, 2021, 6:20 pm ad1c9bdddf
It sounds like you need a list of articles and books. Here you go. You'll find that once you understand Westmoreland's approach (as presented in the first two sources below), you'll see the idea of the "big unit" war and then the later idea of "one approach." You'll find the evidence on both sides of the argument of victory in the other readings.
Winning the Vietnam War: Westmoreland's approach in two documents.
By John M. Carland.
The Journal of Military History, April 2004 v68 i2 p553-574
Abstract: Westmoreland's theory related to the victory in Vietnam is presented in the two documents. One document gives guidance to senior commanders on the way he wanted them to fight the war and the other document evaluates the performance of the troops and gives recommendations for improvement.
Vietnam: Four American Perspectives: Lectures by George S. McGovern, William C. Westmoreland, Edward N. Luttwak, Thomas J. McCormick.
By Patrick J. Hearden (ed)
West Lafayette, IN: Purdue University Press, 1990.
The U.S. military and intelligence services, operating under the political and diplomatic constraints, are assessed within the Vietnam context.