Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
nang co » nang cao, nang doc, nang noi
hieu va » lieu va
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
lai cua » hai cua, lai chau, thai cua
co hoi » co hoc, co loi

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 tu nang co hoi. ((hieu va) OR (hieu qua)) am thuc va danh ((lai cua) OR (dai cua)) triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach tu nang co hoi. ((hieu va) or (hieu qua)) am thuc va danh ((lai cua) OR (dai cua)) triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang co hoi. ((hieu va) or (hieu qua)) am thuc va danh ((lai cua) OR (dai cua)) triet*.