Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
hieu va » lieu va, hieu qua
hieu ve » hieu van
tu sach » thu sach, su sach, tu cach
te sach » toc sach
y nang » ky nang, ly nang, v nang
bac so » bac son, bac si, bac bo
so van » su van, vo van
x hoi » xa hoi, o hoi, x ho
di su » doi su, ki su, da 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) or (te sach)) y nang x hoi. ((hieu ve) or (hieu va)) bac so van hanh di su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) y nang x hoi. ((hieu ve) OR (hieu va)) bac so van hanh di su triet.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) y nang x hoi. ((hieu ve) or (hieu va)) bac so van hanh di su triet*.