Perhaps you should try some spelling variations:
vanh dai » van dai, vanh tai, lanh dao
hanh dai » hanh tai, hanh dao, thanh dat
chat tuc » chat xuc, luat tuc, chat huu
trang va » tran van, hang va
tu sach » thu sach, su sach, te sach
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
tang xa » trang xa, tang ma, lang xa
thiet » thieu

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) or (trang va)) hoi. hieu va chat tuc xa ((hanh dai) OR (vanh dai)) va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((tang xa) OR (trang va)) hoi. hieu va chat tuc xa ((hanh dai) OR (vanh dai)) va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((tang xa) or (trang va)) hoi. hieu va chat tuc xa ((hanh dai) OR (vanh dai)) va thiet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((tang xa) or (trang va)) hoi. hieu va chat tuc xa ((hanh dai) OR (vanh dai)) va thiet*.