How many movies have Hồng Ngọc and Nguyễn Quý Viện collaborated on?

They have worked on 3 movies together! Their first movie together was Cards on the Table: The Gunshot on the Highland (1983) and was their highest rated movie together. They have not worked together since Cards on the Table: Blue Sky in the Split of Leaf (1985). They are most known for their war films together.