Perhaps you should try some spelling variations:
cac nuoc » hoc nuoc, dat nuoc, cua nuoc
cap nuoc » dat nuoc
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
hieu va » lieu va
dao lai » dao lam, dao bai, dao hai
lai cua » dai cua, hai cua, lai chau
va dao » ca dao
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach _ lang xa hoi. ((hieu va) OR (hieu qua)) ((cac nuoc) or (cap nuoc)) va dao lai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach _ lang xa hoi. ((hieu va) OR (hieu qua)) ((cac nuoc) OR (cap nuoc)) va dao lai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach _ lang xa hoi. ((hieu va) OR (hieu qua)) ((cac nuoc) or (cap nuoc)) va dao lai cua te".
• Adding a wildcard symbol may retrieve word variants: tu sach _ lang xa hoi. ((hieu va) OR (hieu qua)) ((cac nuoc) or (cap nuoc)) va dao lai cua te*.