Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
vat dinh » van dinh, vat sinh, vao dinh
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
va dinh » van dinh, va kinh, va tinh
dai su » dai sua, dai so, dan su
x hoi » xa hoi, o hoi, x ho
thuc » thu

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