Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
cam quoc » cac quoc, cao quoc, nam quoc
sach ky » sac ky, sach y, sach kem
ban anh » ban hanh, ban banh, ban danh
qua cam » qua cham, qua cac, qua ca
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
anh de » hanh de, anh d, anh ve
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 ky) OR (sach ty)) nang ((xa hoi) or (o hoi)). hieu qua cam quoc ban anh de cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach ty)) nang ((xa hoi) OR (o hoi)). hieu qua cam quoc ban anh de cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) OR (sach ty)) nang ((xa hoi) or (o hoi)). hieu qua cam quoc ban anh de cua tre".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) OR (sach ty)) nang ((xa hoi) or (o hoi)). hieu qua cam quoc ban anh de cua tre*.