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