Perhaps you should try some spelling variations:
ban banh » ban hanh, ban anh, ban danh
quoc ban » quoc bao, quoc lan, quoc quan
cam quoc » cac quoc, cao quoc, nam quoc
hieu va » lieu va, hieu qua
banh de » hanh de, banh keo, thanh de
su sach » so sach
vu sach » vu bach, vu khach
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
de cua » le cua, te cua, dieu cua
o hoi » co hoi, o hoc, o hai

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 (vu sach)) ky nang ((xa hoi) or (o hoi)). hieu va cam quoc ban banh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ky nang ((xa hoi) OR (o hoi)). hieu va cam quoc ban banh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (vu sach)) ky nang ((xa hoi) or (o hoi)). hieu va cam quoc ban banh de cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (vu sach)) ky nang ((xa hoi) or (o hoi)). hieu va cam quoc ban banh de cua tre*.