Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » thien van, lieu va, hieu ve
sach ty » sach y, sach tu, sach thu
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
cac dai » cac dan, cac bai, can dai
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cao hoi » cau hoi, co hoi, cao hoc
ty nang » ky nang, ty xang, ty hang
cac dac » cac dan, cac bac, cac tac
vi cua » vai cua, di cua

You may be able to get more results by adjusting your search query.

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