Perhaps you should try some spelling variations:
hanh gian » thanh gian, thanh giang, manh giang
gian cua » gian xu, ban cua
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
hieu ve » hieu van
hieu va » lieu va, hieu qua
cua te » cua tu
bo va » bao va, do va, so va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ky nang ma hoa. ((hieu ve) or (hieu va)) bao ((bo va) or (ban va)) hanh gian cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ky nang ma hoa. ((hieu ve) OR (hieu va)) bao ((bo va) OR (ban va)) hanh gian cua te.
• Adding a wildcard symbol may retrieve word variants: so sach ky nang ma hoa. ((hieu ve) or (hieu va)) bao ((bo va) or (ban va)) hanh gian cua te*.