Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
dinh tri » chinh tri
ky tang » ky dang, kho tang, ky trong
thuc va » thuc vat, thuc dan, thuc day
dinh vi » dinh ve, dinh viet, dinh thi
cua tre » cua te, cuu tre, cua triet
te bac » ten bac, te bao, te ban

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

• Performing a fuzzy search may retrieve terms with similar spellings: te bac ((ky tang) OR (ky nang)) xa hoi. hieu van nam thuc va ((dinh vi) or (dinh tri)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te bac ((ky tang) OR (ky nang)) xa hoi. hieu van nam thuc va ((dinh vi) OR (dinh tri)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te bac ((ky tang) OR (ky nang)) xa hoi. hieu van nam thuc va ((dinh vi) or (dinh tri)) cua tre".
• Adding a wildcard symbol may retrieve word variants: te bac ((ky tang) OR (ky nang)) xa hoi. hieu van nam thuc va ((dinh vi) or (dinh tri)) cua tre*.