Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
cam quoc » cac quoc, cao quoc, nam quoc
hieu va » lieu va, hieu qua
ban anh » ban hanh, ban banh, ban danh
su sach » vu sach
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
y nang » ky nang, ly nang, v nang
anh ve » hanh ve, anh va, anh viet
ve cua » le cua, de cua, te cua
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) OR (so sach)) y nang ((x hoi) or (o hoi)). hieu va cam quoc ban anh ve cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) y nang ((x hoi) OR (o hoi)). hieu va cam quoc ban anh ve cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) y nang ((x hoi) or (o hoi)). hieu va cam quoc ban anh ve cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) y nang ((x hoi) or (o hoi)). hieu va cam quoc ban anh ve cua tre*.