Perhaps you should try some spelling variations:
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 van
hieu va » lieu va, hieu qua
x hoi » xa hoi, o hoi, x ho
bo va » bao va, do va, so va
su va » su van, tu va
vi su » va su, ve su, ki su

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 va)) bac ((bo va) or (su va)) hanh vi 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 va)) bac ((bo va) OR (su va)) hanh vi 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 va)) bac ((bo va) or (su va)) hanh vi su triet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((hieu ve) OR (hieu va)) bac ((bo va) or (su va)) hanh vi su triet*.