Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
so sanh » do sanh
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
van cac » van hac, van cau, van bac
vi cua » vai cua, di cua
cua te » cua tu
v nang » va nang, vu nang, van nang
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sanh)) v nang ((x hoi) OR (o hoi)). hieu van cac thuc va hanh vi cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sanh)) v nang ((x hoi) OR (o hoi)). hieu van cac thuc va hanh vi cua te~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sanh)) v nang ((x hoi) OR (o hoi)). hieu van cac thuc va hanh vi cua te*.