Perhaps you should try some spelling variations:
vat hanh » vat thanh, van hanh, va hanh
nam thuc » nam thuoc, am thuc, nam thu
vu sach » vu bach, vu khach
hieu va » lieu va, hieu qua
hieu ve » hieu van
su sach » so sach
v nang » va nang, vu nang, van nang
vi cua » vai cua, di cua
cua te » cua tu
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: ((vu sach) OR (su sach)) v nang x hoi. ((hieu ve) or (hieu va)) nam thuc vat hanh vi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sach) OR (su sach)) v nang x hoi. ((hieu ve) OR (hieu va)) nam thuc vat hanh vi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sach) OR (su sach)) v nang x hoi. ((hieu ve) or (hieu va)) nam thuc vat hanh vi cua te".
• Adding a wildcard symbol may retrieve word variants: ((vu sach) OR (su sach)) v nang x hoi. ((hieu ve) or (hieu va)) nam thuc vat hanh vi cua te*.