Perhaps you should try some spelling variations:
cua triet » cua viet, su triet, va triet
thuc day » thuc dan, thuc vat
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, dua tren
dinh va » dinh van, dinh ve, tinh va
te sach » toc sach
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
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 sach ky lang xa hoi. hieu van am ((thuc va) or (thuc day)) dinh va ((cua tre) OR (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ky lang xa hoi. hieu van am ((thuc va) OR (thuc day)) dinh va ((cua tre) OR (cua triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ky lang xa hoi. hieu van am ((thuc va) or (thuc day)) dinh va ((cua tre) OR (cua triet))".
• Adding a wildcard symbol may retrieve word variants: te sach ky lang xa hoi. hieu van am ((thuc va) or (thuc day)) dinh va ((cua tre) OR (cua triet))*.