Perhaps you should try some spelling variations:
su triet » su viet, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cac tac » cac toc, cac bac, cac dac
hieu va » lieu va, hieu qua
tang xa » trang xa, tang ma, lang xa
hieu ve » hieu van
ky tang » ky nang, ky dang, kho tang
su tien » su kien, su hien, tu tieng
tac va » tac da, tac xa, tuc va
va dan » ca dan, va dao, va dau
dan va » doan va, dan ca, ban 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 ky tang xa hoi. ((hieu ve) or (hieu va)) cac tac va dan va ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky tang xa hoi. ((hieu ve) OR (hieu va)) cac tac va dan va ((su triet) OR (su tien)).
• Adding a wildcard symbol may retrieve word variants: tu sach ky tang xa hoi. ((hieu ve) or (hieu va)) cac tac va dan va ((su triet) or (su tien))*.