Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
hieu quan » lieu quan, thien quan, lien quan
doan van » doan va, hoang van, luan van
thuoc ma » hoc ma, duoc ma
cua tre » cua te, cuu tre, cua triet
van cua » vang cua, ban cua, dan cua
ky tang » ky nang, ky dang, kho tang
tang ha » lang ha, tang ma, trung ha
ma doan » ma dan, tap doan, va doanh
te cac » tu cac, ve cac, de cac
ha hoi » hoa hoi, ha noi, xa hoi
te cao » te bao

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te cac) or (te cao)) ky tang ha hoi. ((hieu quan) or (hieu qua)) nam thuoc ma doan van cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te cac) OR (te cao)) ky tang ha hoi. ((hieu quan) OR (hieu qua)) nam thuoc ma doan van cua tre.
• Adding a wildcard symbol may retrieve word variants: ((te cac) or (te cao)) ky tang ha hoi. ((hieu quan) or (hieu qua)) nam thuoc ma doan van cua tre*.