Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
hieu luat » hieu qua
thanh cho » thanh pho, thanh cha, thanh chu
cho nguoi » cua nguoi
viet nami » viet nam, vien nam, viet nang
tien duan » tien dua, tien huan, tien quang
hoc tien » hoc tieng, hoc hien, hoc vien
viet nm » viet nam, viet anh, viet ngu

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

• Performing a fuzzy search may retrieve terms with similar spellings: giao trinh ((hieu quan) or (hieu luat)) thanh cho nguoi ((viet nm) or (viet nami)) hoc tien duan~.
• If you are trying to use Boolean operators, they must be ALL CAPS: giao trinh ((hieu quan) OR (hieu luat)) thanh cho nguoi ((viet nm) OR (viet nami)) hoc tien duan.
• Adding a wildcard symbol may retrieve word variants: giao trinh ((hieu quan) or (hieu luat)) thanh cho nguoi ((viet nm) or (viet nami)) hoc tien duan*.