Perhaps you should try some spelling variations:
quoc ban » quoc bao, quoc lan, quoc quan
tu sach » thu sach, su sach, te sach
qua cam » qua cham, qua cac, qua ca
xuc ban » duc ban, cuc ban, xuat ban
anh doi » anh noi, anh doc, thanh doi
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
y hang » ly hang, ty hang, yu hang
co hai » co dai, co hoi, so hai
o hai » so hai, o lai, _ hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach y hang ((o hai) or (co hai)). hieu qua cam ((xuc ban) or (quoc ban)) anh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y hang ((o hai) OR (co hai)). hieu qua cam ((xuc ban) OR (quoc ban)) anh doi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y hang ((o hai) or (co hai)). hieu qua cam ((xuc ban) or (quoc ban)) anh doi cua tre*.