Tran Thi Lan wrote an article on the pronunciation problems of Vietnamese learners. You could try to find that on the internet.
Michael Swan’s Learner English has been updated to include a section on South Asia. This book is a classic on the problems encountered by learners of different nationalities. This might give you some insight.
I suggest you read generally on the subject of intonation. You haven’t said whether you are interested in the topic because you are teaching or whether it is for research or theoretical purposes. Your choice of book will depend on your aim. Sound Foundations by Adrian Underhill contains sections on intonation. The theory is dealt with at length and there is also a section on problems and how to deal with them. The Pronunciation Power CD also has excellent activities for practising intonation.
I also suggest you look at articles and books from Vietnamese publishers and articles produced by Vietnamese professors.