Perhaps you should try some spelling variations:
nam thuoc » nam thuc, nam thu, nha thuoc
hieu van » thien van, lieu va, hieu ve
thuoc va » thuc va, thuoc ma, thuong va
tu sach » thu sach, te sach, tu cach
vai cua » dai cua, hai cua, lai cua
dan vai » dan va, dan tai, dan vat
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
nang ma » tang ma, sang ma, nang cao
su sach » so sach, vu sach
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ky nang ma hoi. ((hieu van) or (hieu va)) nam thuoc va dan vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang ma hoi. ((hieu van) OR (hieu va)) nam thuoc va dan vai cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang ma hoi. ((hieu van) or (hieu va)) nam thuoc va dan vai cua tre*.