Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
tai cua » thai cua, tai cuc, tri cua
dan tai » van tai, dan thi, han tai
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va
tu sach » thu sach, su sach, tu cach
te sach » toc sach
nang o » nang co, nang ho, nang ro
va dan » ca dan, va dao, va dau
o hoi » co hoi, o hoc, o hai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang o hoi. ((hieu ve) OR (hieu van)) am thuc va dan tai cua viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky nang o hoi. ((hieu ve) OR (hieu van)) am thuc va dan tai cua viet~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang o hoi. ((hieu ve) OR (hieu van)) am thuc va dan tai cua viet*.