Perhaps you should try some spelling variations:
hien thuan » thien thuat
trinh hieu » trinh dieu, trinh thiet, trinh nhiet
cho nguoi » cua nguoi
hien huan » hien quan, tien huan, thien quan
qua danh » qua dan, luan danh, luat danh
viet nma » viet nami, viet nhat, viet nam
viet nm » viet nam, viet nami, viet anh

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: giao trinh hieu qua danh cho nguoi ((viet nma) OR (viet nm)) hoc ((hien huan) OR (hien thuan))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "giao trinh hieu qua danh cho nguoi ((viet nma) OR (viet nm)) hoc ((hien huan) or (hien thuan))~".
• Adding a wildcard symbol may retrieve word variants: giao trinh hieu qua danh cho nguoi ((viet nma) OR (viet nm)) hoc ((hien huan) or (hien thuan))*.