Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
ban thanh » ban hanh, ban hang
va triet » va thiet, va trien, ve triet
suu ban » cuu ban, huu bang, luu bang
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
hieu ha » hieu hoa, hieu ca, hieu xa
nang ma » tang ma, sang ma, mang may
dai va » mai va

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 ty ((nang ma) OR (nang cao)) hoi. ((hieu ha) OR (hieu va)) nam suu ban thanh dai va triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((nang ma) or (nang cao)) hoi. ((hieu ha) OR (hieu va)) nam suu ban thanh dai va triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang ma) or (nang cao)) hoi. ((hieu ha) OR (hieu va)) nam suu ban thanh dai va triet*.