Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
hieu van » hieu va, thien van, lieu va
thanh vi » hanh vi, thanh va, thanh ve
sang dai » sang tai, lang dai, sang mai
van lam » van nam
cua tre » cuu tre, cua triet, dua tren
duc ban » duc tan, duc van, dua ban
lam duc » lam duoc, pham duc, nam duoc
dai hoi » dai hoc, dai hai, dai moi
san ky » sang ky, van ky, ban ky
dan ky » van ky
cua te » cua tu

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: phu ((san ky) OR (dan ky)) sang dai hoi. hieu van lam duc ban thanh vi ((cua tre) OR (cua te))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "phu ((san ky) or (dan ky)) sang dai hoi. hieu van lam duc ban thanh vi ((cua tre) OR (cua te))~".
• Adding a wildcard symbol may retrieve word variants: phu ((san ky) or (dan ky)) sang dai hoi. hieu van lam duc ban thanh vi ((cua tre) OR (cua te))*.