Perhaps you should try some spelling variations:
thuc day » thuc dan, thuc vat
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
ky tang » ky nang, kho tang, ky trong
ky dang » ky nang, ky danh
dinh va » dinh van, dinh ve, tinh va
thuc va » thuc vat, thuc dan
va cua » va chua, via cua, ca cua
te sac » te sach, te cac, te san
van am » van nam, van lam, van dam

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

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