Perhaps you should try some spelling variations:
hieu van » thien van, lieu va
van hanh » van thanh, ban hanh, van anh
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
bo van » vo van, so van, do van
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho

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