Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
thu mang » thu hang, thu bang, thu sang
thu dang » thu hang, thu bang, thu dong
dan vat » dang vat, van vat, dan va
tu sach » thu sach, su sach, te sach
lai roi » lai hoi, loi roi
hieu va » hieu qua
co duc » co duoc, cao duc, do duc
va dan » ca dan, va dao, va dau
vat va » dat va

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 ((thu mang) OR (thu dang)) lai roi. ((hieu va) or (lieu va)) co duc va dan vat va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((thu mang) OR (thu dang)) lai roi. ((hieu va) OR (lieu va)) co duc va dan vat va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((thu mang) OR (thu dang)) lai roi. ((hieu va) or (lieu va)) co duc va dan vat va triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((thu mang) OR (thu dang)) lai roi. ((hieu va) or (lieu va)) co duc va dan vat va triet*.