Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
chat tuc » chat xuc, luat tuc, chat huu
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu ve » hieu va
xa hanh » xa thanh, xa khanh, va hanh
vai va » dai va, hai va, lai va
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: thu sach ky tang xa hoi. ((hieu ve) or (hieu van)) chat tuc xa hanh ((vai va) OR (mai va)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky tang xa hoi. ((hieu ve) OR (hieu van)) chat tuc xa hanh ((vai va) OR (mai va)) thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky tang xa hoi. ((hieu ve) or (hieu van)) chat tuc xa hanh ((vai va) OR (mai va)) thiet".
• Adding a wildcard symbol may retrieve word variants: thu sach ky tang xa hoi. ((hieu ve) or (hieu van)) chat tuc xa hanh ((vai va) OR (mai va)) thiet*.