Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
dai hoi » dai hoc, dai hai, dai moi
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
dan va » doan va, dan ca, ban va
vi cua » vai cua, di cua

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 nang ((xa hoi) or (dai hoi)). ((hieu van) OR (lieu va)) cac dan va danh vi cua vat~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((xa hoi) OR (dai hoi)). ((hieu van) OR (lieu va)) cac dan va danh vi cua vat.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((xa hoi) or (dai hoi)). ((hieu van) OR (lieu va)) cac dan va danh vi cua vat".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((xa hoi) or (dai hoi)). ((hieu van) OR (lieu va)) cac dan va danh vi cua vat*.